# Eating Disorders Concurrent with Type 1 Diabetes: Prevalence, Clinical Outcomes, and Management of Deliberate Insulin Omission (Diabulimia)

## A Comprehensive Narrative Review

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### Background and Context

Type 1 diabetes mellitus (T1DM) is among the most demanding chronic conditions in medicine, requiring individuals to engage in continuous, cognitively intensive self-management: frequent blood glucose monitoring, carbohydrate counting, insulin dose calculation, and adjustment for physical activity and illness. These demands are not merely logistical; they impose a sustained psychological burden that fundamentally restructures an individual's relationship with food, body weight, and self-image. It is within this context that the co-occurrence of eating disorders (EDs) and T1DM has emerged as one of the most clinically consequential and underrecognised comorbidities in endocrinology and psychiatry. The intersection of these two conditions creates a uniquely dangerous clinical scenario, particularly when individuals exploit the pharmacological mechanism of insulin to achieve weight loss — a behaviour colloquially termed "diabulimia" and more precisely described in the scientific literature as intentional insulin omission (IIO) or insulin restriction for weight control (IRWC).

The epidemiological signal is unambiguous: women with T1DM have approximately 2.5 times the risk of developing a diagnosable eating disorder compared to women without diabetes (PMC6637645). A meta-analysis of 14 studies quantified the relative risk of any eating disorder in T1DM at 2.47 (95% CI 1.84–3.32), with particularly elevated risk for bulimia nervosa and binge eating disorder (PMC12983690). Disordered eating behaviours (DEBs) — a broader category encompassing subclinical patterns that do not meet full diagnostic criteria — are even more prevalent, with estimates ranging from 8.69% to 59% across international studies of adolescents with T1DM (PMC10521451). The specific behaviour of IIO, in which insulin doses are deliberately reduced or omitted to induce glycosuria and caloric wasting as a weight-loss strategy, has been documented in 20%–45% of T1DM populations depending on the assessment methodology and population studied (PMC13163752). Endorsing insulin restriction alone was associated with a 3-fold increase in mortality risk over an 11-year period (PMC6637645). These figures establish IIO not merely as a behavioural curiosity but as a major driver of preventable morbidity and premature death in a population already burdened by chronic disease.

Despite this evidence, diabulimia lacks formal diagnostic recognition in either the DSM-5 or ICD-11, is classified only loosely under "drug abuse to ensure undefined eating disorder/weight loss" in the DSM-5 framework, and is chronically underdetected in clinical practice (PMC13163752). Sixty-five percent of patients with IIO report never having disclosed the behaviour to their physician, citing shame, stigma, and a perception that healthcare providers focus exclusively on insulin adherence without addressing the underlying psychological distress (PMC13163752). The 2017 NICE guidelines for eating disorders included, for the first time, a section on diabetes and insulin restriction — though without formally recognising the term "diabulimia" — marking an important but incomplete step toward clinical recognition (PMC7513317). The present review synthesises the available evidence on the prevalence, psychosocial mechanisms, metabolic consequences, screening approaches, and management strategies for eating disorders concurrent with T1DM, with particular focus on IIO. It draws on a body of literature spanning cross-sectional epidemiological studies, qualitative investigations of lived experience, systematic reviews, and emerging pilot service evaluations to provide a comprehensive, quantitatively grounded synthesis for clinicians and researchers working at the intersection of endocrinology and mental health.

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### Molecular and Mechanistic Pathways

#### The Pharmacological Basis of Insulin Omission as a Weight-Loss Strategy

The mechanism by which IIO produces weight loss is straightforward and rooted in the fundamental physiology of insulin action. Insulin is the primary anabolic hormone responsible for facilitating cellular glucose uptake, suppressing hepatic glucose production, and promoting lipid and protein synthesis. In the absence of adequate insulin, blood glucose rises when insulin is withheld, resulting in a rapid breakdown of proteins (catabolism) as well as rapid calorie loss through glycosuria — the excretion of glucose in urine. This combination of glycosuria-mediated caloric wasting and accelerated catabolism produces rapid, visible weight loss that individuals with T1DM can exploit deliberately by reducing or omitting insulin doses (PMC7513317).

The weight loss achieved through IIO is therefore mechanistically distinct from the caloric restriction or purging behaviours seen in anorexia nervosa or bulimia nervosa, respectively. Rather than restricting intake or expelling ingested food, the individual with IIO can consume food normally — or even in excess — while preventing its metabolic utilisation through insulin deprivation. This has been described by patients as a "secret trick" that allows eating without weight gain (PMC7513317). The perceived efficacy of this strategy, at least in the short term, is a powerful reinforcer of the behaviour. However, the same mechanism that produces weight loss also generates severe metabolic consequences. The systematic review by Manzoni et al. (PMC13163752) confirms that IIO is consistently associated with higher HbA1c values, poor glycaemic control, a significant increase in hospitalisations for diabetic ketoacidosis (DKA), and an elevated risk of chronic complications including diabetic retinopathy, neuropathy, and nephropathy.

A clinically important paradox has been documented in the longitudinal literature. The systematic review by Manzoni et al. (PMC13163752) notes that women who continue or initiate IIO tend to gain weight over time, despite the explicit goal of preventing weight increase, and that this finding reinforces the hypothesis that restriction not only fails as a weight-control strategy but also contributes to the maintenance of a vicious cycle of insulin fear, thus impairing the management of diabetes. This paradox has direct implications for therapeutic education, as it challenges the core belief that drives IIO and provides a factual basis for motivational intervention.

#### Gut Microbiota Alterations as a Biological Mediator

An emerging mechanistic hypothesis concerns the role of gut microbiota alterations in mediating the metabolic deterioration observed in patients with IIO and DEBs. A study by Igudesman and colleagues, identified in the systematic review by Manzoni et al. (PMC13163752), found that DEBs and IIO are associated with unfavourable alterations in gut microbiota composition. Specifically, IIO was associated with a decrease in *Lachnospira*, while increased DEBs were associated with a reduction in *Anaerostipes*. Both bacterial genera are producers of short-chain fatty acids (SCFAs), key molecules involved in glycaemic regulation, modulation of systemic inflammation, and maintenance of intestinal barrier integrity. The reduction of SCFA-producing taxa in individuals with IIO and DEBs suggests a potential microbiota-mediated contribution to the metabolic deterioration observed in these patients, beyond the direct effects of insulin deficiency alone (PMC13163752).

This hypothesis is preliminary and based on a single observational study, but it opens an important avenue for future research. If gut microbiota profiles can be identified as biological biomarkers of IIO or DEBs, they could potentially serve as objective screening tools that complement self-report measures — which are subject to significant underreporting due to shame and stigma. The mechanistic link between SCFA depletion, impaired glycaemic regulation, and the psychological dimensions of eating disorder pathology (including mood dysregulation and impulsivity) also warrants further investigation, as it may help explain why IIO is so difficult to interrupt even when patients are fully aware of its consequences.

#### Psychological and Neurobiological Mechanisms of Maintenance

Beyond the pharmacological mechanism of weight loss, the psychological mechanisms that initiate and maintain IIO are complex and multifactorial. The systematic review by Manzoni et al. (PMC13163752) identifies several overlapping psychological pathways. Fear of weight gain associated with insulin therapy is consistently identified as a key predictor of whether insulin restriction is initiated and maintained over time. The editorial by Goebel-Fabbri (PMC6637645) notes that women and girls with T1DM often have a higher BMI than their peers without diabetes, and that disturbed eating behaviours in T1DM are strongly predicted by higher BMI, higher shape and weight concerns, lower self-esteem, and depressed mood. The weight gain that follows insulin initiation at diagnosis — after a period of pre-diagnostic weight loss due to uncontrolled hyperglycaemia — is a particularly potent trigger for body dissatisfaction and the subsequent development of DEBs (PMC7513317, PMC13163752).

Second, IIO appears to function as a maladaptive emotion regulation strategy. Merwin and colleagues, cited in the systematic review (PMC13163752), demonstrated that IIO is more strongly predicted by the subjective appraisal of an eating episode — such as the perception of having broken a dietary rule, having lost control, or having experienced guilt — than by the objective characteristics of the food consumed. Even mild but transient increases in negative affect were sufficient to double the likelihood of IIO. This finding positions IIO within the broader framework of emotion dysregulation that characterises many eating disorders, and suggests that interventions targeting affect regulation may be particularly important in this population.

Third, the qualitative literature documents a self-harm function of IIO in a minority of patients. In the study by Coleman et al. (PMC7513317), 4% of participants (2/45) stated that self-harm was the primary reason for insulin restriction, describing intentional hyperglycaemia as "emotional anaesthesia" or self-punishment. This finding, while representing a minority of cases, has important clinical implications: it suggests that IIO can serve functions analogous to non-suicidal self-injury in some individuals, and that standard eating disorder treatment frameworks may need to be supplemented with trauma-informed approaches and self-harm risk assessment.

The qualitative meta-synthesis by Goddard and Oxlad, incorporated into the review by Patel et al. (PMC10691075), provides a complementary framework through the lens of diabetes distress (DD). Mapping patient experiences onto the seven subscales of the Type 1 Diabetes Distress Scale (T1D-DDS), the authors found evidence of DD across all seven subscales in individuals with diabulimia. The most commonly met criteria included "Feeling that people treat me differently when they find out I have diabetes" (Negative Social Perceptions subscale, item 4), "Feeling that my friends or family act like 'diabetes police'" (Friend/Family Distress subscale, item 20), "Feeling that I am not as skilled at managing diabetes as I should be" (Management Distress subscale, item 1), and "Feeling that no matter how hard I try with my diabetes, it will never be good enough" (Powerlessness subscale, item 25) (PMC10691075). These findings suggest that the chronic psychological burden of T1DM self-management — encompassing feelings of inadequacy, social stigma, family conflict, and powerlessness — creates a fertile psychological environment for the development of IIO as a coping strategy.

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### Dose-Response and Pharmacokinetics

#### The Relationship Between Degree of Insulin Restriction and Metabolic Outcomes

While the literature does not report dose-response relationships in the pharmacokinetic sense applicable to drug studies, there is a meaningful analogue in the relationship between the frequency and severity of IIO and the degree of metabolic deterioration. The systematic review by Manzoni et al. (PMC13163752) synthesises evidence showing that the more frequently insulin is omitted or reduced, the higher the mean blood glucose levels and the greater the time spent in hyperglycaemia, leading to further deterioration of metabolic status. This dose-dependent relationship between IIO frequency and glycaemic control is clinically important because it suggests that even partial reduction in IIO frequency — rather than complete cessation — may confer meaningful metabolic benefit.

Critically, the duration of IIO has been shown to be a more robust predictor of complication development than baseline HbA1c levels (PMC13163752). This finding, derived from longitudinal data, implies that the cumulative exposure to insulin deficiency — rather than any single cross-sectional measure of glycaemic control — drives the progressive organ damage associated with diabulimia. It also has implications for clinical monitoring: HbA1c alone may underestimate the risk of complications in patients with intermittent IIO, because periods of adequate insulin use between episodes of restriction can partially normalise the HbA1c value while the cumulative vascular damage continues to accrue.

The cross-sectional data from the Saudi Arabian study by Alaqeel et al. (PMC9961766) provides quantitative illustration of this relationship. Participants with DEBs had significantly higher HbA1c than those without (p < 0.001, Cohen's d = 0.87, a large effect size), and insulin restrictors specifically had a mean HbA1c of 9.2 ± 2.2% compared to lower values in non-restrictors (p < 0.001). The DEPS-R score correlated with HbA1c in both females (r = 0.365, p < 0.001) and males (r = 0.492, p < 0.001), confirming that the severity of disordered eating — not merely its presence or absence — is linearly associated with glycaemic deterioration. Similarly, the Ethiopian cross-sectional study by Haile et al. (PMC10521451) found significantly higher DEPS-R scores among overweight adolescents (median 27, IQR ±25) compared to those with normal weight (median 18, IQR ±15) and those who were thin (median 15, IQR ±13), with a statistically significant difference across BMI-for-age categories (Kruskal-Wallis X² = 23.8, p < 0.001).

#### Screening Thresholds and Their Clinical Calibration

The Diabetes Eating Problem Survey–Revised (DEPS-R) has emerged as the most widely validated diabetes-specific screening tool for DEBs, with a recommended cut-off score of ≥20 (out of a possible 80) indicating high risk for an eating disorder and the need for further clinical assessment (PMC9961766, PMC10521451, PMC13163752). This threshold has been applied across multiple populations and languages; the Ethiopian version demonstrated acceptable internal consistency (Cronbach's alpha 0.86) (PMC10521451), and the Italian exploratory study similarly employed the ≥20 threshold in a sample of youth with T1DM (PMC7761849). The DEPS-R includes items specifically addressing insulin manipulation — a critical advantage over general eating disorder screening tools such as the EAT-26 or SCOFF, which do not capture this diabetes-specific behaviour.

The NHS England pilot service evaluation (PMC12983690) reported a mean baseline DEPS-R score of 46.1 in patients accepted onto the T1DE care pathway — more than double the clinical threshold of 20. After six months of integrated care, the mean DEPS-R score fell to 41.1, remaining well above the clinical threshold. This finding illustrates the chronicity and treatment-resistance of severe T1DE and underscores the need for realistic expectations about the pace of recovery in this population (PMC12983690).

Studies using the DEPS-R have reported IIO prevalence rates as high as 60.2% in samples of individuals with T1DM aged 13–55 years (PMC13163752), though this figure likely reflects the upper bound of estimates and may be inflated by the inclusion of unintentional insulin omission in some studies. More conservative estimates using the ≥20 DEPS-R threshold report high-risk DEB prevalence of 23.9%–31.8% in adolescents and young adults (PMC13163752), 27.2% in Saudi adolescents and young adults (PMC9961766), and 43.3% in Ethiopian adolescents (PMC10521451). The wide range across studies reflects genuine population heterogeneity as well as methodological differences in assessment tools, cut-off thresholds, and reference periods.

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### Clinical Evidence and Implications

#### Prevalence Estimates Across Populations and Age Groups

The prevalence of DEBs and IIO in T1DM varies substantially across studies, reflecting differences in population characteristics, assessment instruments, and study designs. However, several consistent patterns emerge from the available evidence. A 2026 systematic review by Manzoni et al. (PMC13163752), which included 29 studies involving 8,198 patients with T1DM across 16 countries, reported IIO prevalence ranging from 20% to 45% across populations, depending on the population studied, age group, and assessment instruments employed. Among adolescents and young adults specifically, DEPS-R-based estimates cluster between 23.9% and 31.8%, suggesting that approximately one-quarter to one-third of this age group engages in IIO (PMC13163752). Within this body of evidence, Peyrot and colleagues, cited in the same review, found that 57% of participants had omitted an insulin injection at least once despite being aware of its necessity, while 20% acknowledged omitting injections on a regular basis (PMC13163752).

The Saudi Arabian cross-sectional study (PMC9961766) enrolled 265 participants aged 12–25 years and found that 27.2% scored ≥20 on the DEPS-R, indicating high risk for DEBs. Females had a significantly higher prevalence (32.5%) than males (18.6%; p = 0.01), with mean DEPS-R scores of 16.8 ± 10.9 versus 13.3 ± 10.0, respectively. Insulin restriction was reported by 27.5% of participants, and 12.1% reported skipping insulin doses at least occasionally after overeating. Notably, 59.7% of insulin restrictors scored ≥20 on the DEPS-R compared with only 15.1% of non-restrictors (p < 0.001), confirming the strong association between IIO and broader DEB pathology.

The Ethiopian hospital-based study (PMC10521451) reported the highest overall DEB prevalence in the reviewed literature: 43.3% (95% CI: 38.3%–48.3%) among 395 adolescents with T1DM aged 10–19 years. This figure is notable because it derives from a low-income country context where such data are scarce, and it challenges the assumption that DEBs in T1DM are primarily a phenomenon of high-income, Western societies. The prevalence of purging behaviours was lower than in Western samples — insulin skipping was reported by 7.6% and insufficient insulin dosing by 10.9% — while non-purging behaviours such as alternating meals (46.6%) and avoiding blood sugar checks (26.6%) were more common. This pattern may reflect cultural differences in the expression of DEBs, or it may reflect the lower BMI and different body image norms in this population.

The Italian exploratory study (PMC7761849) enrolled 40 youth with T1DM aged 11–18 years and found that 8 (20%) scored ≥20 on the DEPS-R, consistent with the lower end of estimates from other studies. The COVID-19 lockdown study (PMC7708884), which compared 138 Italian youth with T1DM to 276 matched healthy controls during April 2020, found no statistically significant difference in DEB frequency between groups (8.69% vs. 13.4% scoring ≥20 on the ChEAT/EAT-26; p = 0.162). However, the authors explicitly acknowledged that the ChEAT and EAT-26 do not capture insulin manipulation, and that this limitation likely led to underestimation of DEBs in the T1DM group — a methodological point with important implications for the interpretation of prevalence data across studies using non-diabetes-specific tools.

#### Gender Differences in Prevalence and Severity

The literature consistently documents a female predominance in DEBs and IIO in T1DM, though the magnitude of the gender difference varies across studies and some recent evidence suggests the gap may be narrowing. The systematic review by Manzoni et al. (PMC13163752) notes that since the earliest investigations, the literature has documented female predominance: Polonsky and colleagues found regular IIO in 30.5% of women, and Khan and Montgomery found that 22.9% of young women reported IIO at least once per month. Wisting and colleagues observed that 36.8% of adolescent girls reported insulin restriction and 26.2% reported complete omission of doses; longitudinal studies in adult populations have reported that more than 30% of women engage in IIO (PMC13163752).

However, several more recent studies have reported attenuated or absent gender differences, particularly during adolescence (PMC13163752). The Saudi Arabian study found no statistically significant difference between males and females in insulin restriction (29.4% vs. 24.5%) or omission (13.5% vs. 9.8%; p > 0.05 for both) (PMC9961766). The Ethiopian study found similar DEB prevalence in females (21.8%) and males (21.5%), with no significant difference in DEPS-R scores between genders (p = 0.793) (PMC10521451). The qualitative study by Coleman et al. (PMC7513317) was almost entirely female (42/45 participants), reflecting both the genuine female predominance in help-seeking for eating disorders and the methodological challenge of recruiting male participants to eating disorder research.

The NHS England pilot service evaluation (PMC12983690) reported that 89% of patients accepted onto the T1DE care pathway were female, consistent with the broader literature. However, the authors noted that one study has suggested insulin restriction or omission may be just as prevalent among males, and that the evidence regarding ethnic origin is lacking. The systematic review (PMC13163752) explicitly flags that the purported higher prevalence of IIO in female patients is not confirmed by several studies, and that the fact that many studies enrolled exclusively female samples renders the observed gender differences unreliable. This is an important caveat that should inform both clinical practice (avoiding the assumption that IIO is exclusively a female problem) and future research design.

#### Age of Onset and Developmental Trajectories

Adolescence is consistently identified as the period of highest vulnerability for the onset of DEBs and IIO in T1DM, though the behaviour is not confined to this developmental phase. The systematic review (PMC13163752) reports that IIO typically begins around 19 years of age, with a wide range of 12–45 years documented across studies. The qualitative study by Coleman et al. (PMC7513317) found a mean age of first insulin restriction of 19.31 years (SD = 7.70), with a minimum of 12 and a maximum of 45, confirming that IIO can emerge in midlife as well as in adolescence and young adulthood.

The Ethiopian study (PMC10521451) found that late adolescence (ages 15–19) was associated with approximately twice the odds of DEBs compared to early adolescence (ages 10–14) (AOR = 2.10, 95% CI: 1.33–3.34), consistent with Norwegian data showing DEB prevalence of 41.2% among adolescents aged 17–19 years, 19.8% among those aged 14–16 years, and only 3.6% among those aged 11–13 years. The Saudi Arabian study found no significant difference in DEB prevalence between adolescents (27.7%) and young adults (26.3%), suggesting that the elevated risk established in adolescence persists into young adulthood rather than resolving with age (PMC9961766). This finding is consistent with a 10-year longitudinal study cited in the Saudi paper showing that the prevalence of disordered eating remained constant or increased from adolescence to young adulthood.

The prevalence of diabulimia has been estimated at approximately 2% among preadolescent girls, increasing to 11–15% in adolescents and reaching 30–39% in young women aged 12–18 years, highlighting a marked age-related increase in risk (PMC13163752). This developmental trajectory has important implications for the timing of screening and preventive interventions: the window between T1DM diagnosis and the onset of IIO — which may be as short as a few years in adolescent girls — represents a critical opportunity for early psychological support.

#### Metabolic Consequences: HbA1c, DKA, and Microvascular Complications

The metabolic consequences of IIO are severe and well-documented across the reviewed literature. Women with T1DM and eating disorders have HbA1c values approximately 2 or more percentage points higher than similarly aged women with T1DM without eating disorders (PMC6637645). The Saudi Arabian study quantified this difference with a large effect size: participants with DEBs had significantly higher HbA1c than those without (p < 0.001, Cohen's d = 0.87), and insulin restrictors specifically had a mean HbA1c of 9.2 ± 2.2% (PMC9961766). The NHS England pilot service evaluation reported a mean baseline HbA1c of 11.2% in patients accepted onto the T1DE care pathway — far above the recommended target of ≤7% — with a mean reduction to 10.2% after six months of integrated care (PMC12983690).

Hospitalisation for DKA is a particularly important clinical outcome associated with IIO. The Saudi Arabian study found that a history of DKA admission in the previous six months was significantly more common in patients with DEBs (16.7%) than in those without (7.8%; p = 0.033) (PMC9961766). The qualitative study by Coleman et al. (PMC7513317) found that 73% of participants (33/45) had received medical or psychiatric intervention because of their insulin misuse, with the majority describing treatment for DKA, often on multiple occasions. Patients described becoming "seriously ill on multiple occasions" and one participant stated "I've been in DKA more times than I can remember." The systematic review by Manzoni et al. (PMC13163752) confirms that IIO is associated with severe medical consequences including a significant increase in hospitalisations for DKA and an elevated risk of chronic complications, particularly diabetic retinopathy, neuropathy, and nephropathy.

The longitudinal evidence on microvascular complications is particularly sobering. The systematic review (PMC13163752) reports that IIO is associated with an elevated risk of chronic complications including diabetic retinopathy, neuropathy, and nephropathy, with longitudinal studies demonstrating an association between IIO and an increased incidence of microvascular complications, foot-related problems, and mortality. The duration of IIO — rather than baseline HbA1c — is the more robust predictor of complication development, underscoring the cumulative and progressive nature of the organ damage (PMC13163752). The Ethiopian study (PMC10521451) found that having diabetic complications was associated with more than twice the odds of DEBs (AOR = 2.32, 95% CI: 1.43–3.75), though the cross-sectional design precludes determination of the causal direction of this relationship.

#### Mortality Risk

The mortality data associated with IIO are among the most striking findings in the literature. Endorsing just insulin restriction alone was associated with a 3-fold increase in mortality risk over an 11-year period (PMC6637645). The systematic review (PMC13163752) further reports that IIO is associated with an average reduction in life expectancy of approximately 13 years, establishing it as a reliable predictor of mortality. In the same longitudinal study, deceased women exhibited significantly higher HbA1c levels, higher BMI, and more severe eating disorder symptomatology, which was associated with more frequent IIO. These figures position diabulimia as one of the most lethal eating disorder presentations in clinical medicine, comparable in mortality risk to anorexia nervosa.

#### Psychological Comorbidities and Their Clinical Significance

The psychological burden associated with IIO extends well beyond the eating disorder itself. The systematic review (PMC13163752) reports that the presence of a psychiatric disorder confers an almost sixfold increased risk of diabetes-specific eating disorder (DSED), with anxious-depressive symptomatology emerging as the main predictive factor. Individuals with depression face an approximately fivefold increased risk of developing behaviours consistent with diabulimia compared to those without depressive symptoms. The bidirectional relationship between depression and DEBs is clinically important: depression may increase vulnerability to DEBs through impaired motivation and self-efficacy, while feelings of guilt and frustration associated with poor glycaemic control may, in turn, exacerbate depressive symptoms (PMC13163752).

The qualitative study by Coleman et al. (PMC7513317) found that the most common comorbid mental health difficulties discussed by participants were other eating disorders, depression, and stress. Participants described having nobody to talk to due to feelings of shame and a lack of understanding from others. The diabetes distress meta-synthesis (PMC10691075) found evidence of DD across all seven subscales of the T1D-DDS in individuals with diabulimia, with the Negative Social Perceptions subscale having the most matches (13 participants meeting at least one criterion) and Hypoglycemia Distress having the fewest (4 participants). This pattern suggests that the social and relational dimensions of living with T1DM — including stigma, family conflict, and perceived negative judgement from others — are particularly salient drivers of psychological distress in this population.

The EDE-Q data from the Coleman et al. study (PMC7513317) provide quantitative confirmation of the severity of eating disorder psychopathology in individuals with diabulimia. The global EDE-Q score for the sample (mean 3.96, SD = 1.21) was significantly higher than two general population norms (means 1.55 and 1.52; t(1) = −161.68, p = .004) and statistically comparable to two clinical eating disorder samples (means 4.25 and 4.00; t(1) = 1.32, p = .413). Eighty-four percent (38/45) scored above the clinical cut-off of ≥2.50. The systematic review (PMC13163752) corroborates this finding, noting that symptom severity measured by the EDE-Q in individuals with IIO is comparable to that observed in clinically diagnosed eating disorders and significantly higher than normative population values.

#### Psychosocial Risk Factors and Predictors

Multiple psychosocial risk factors for DEBs and IIO in T1DM have been identified across the reviewed literature. Body shape dissatisfaction (BSD) is among the most consistently documented. The Ethiopian study (PMC10521451) found that BSD was present in 20.3% of participants (95% CI: 16.4%–24.6%) and was associated with more than twice the odds of DEBs (AOR = 2.21, 95% CI: 1.28–3.82). The systematic review by Manzoni et al. (PMC13163752) further notes that, among individuals with T1DM, those who misuse insulin to control weight report significantly higher levels of body dissatisfaction than peers who do not engage in this behaviour, despite no differences in BMI — suggesting that the motivation underlying insulin misuse is rooted in psychological body image disturbance rather than actual overweight.

Higher BMI is a consistent predictor of DEBs across studies. The COVID-19 lockdown study (PMC7708884) found that higher zBMI significantly predicted Dieting scores in T1DM participants (β = .283, p = .001). The Saudi Arabian study found that participants with DEBs had significantly higher BMI than those without (p < 0.001, Cohen's d = 0.70) (PMC9961766). The Ethiopian study found that overweight adolescents had approximately twice the odds of DEBs compared to those with normal nutritional status (AOR = 2.25, 95% CI: 1.32–3.82) (PMC10521451). The editorial by Goebel-Fabbri (PMC6637645) notes that disturbed eating behaviours in T1DM are strongly predicted by higher BMI, higher shape and weight concerns, lower self-esteem, and depressed mood, while positive feelings about appearance, the absence of depression, and a lower BMI may be protective factors.

Family dynamics represent another important risk domain. Among Ethiopian adolescents with T1DM, those with a family history of diabetes mellitus were 1.6 times more likely to have DEBs (AOR = 1.59, 95% CI: 1.03–2.47) compared with those without a family history, though the authors note that no direct causal mechanism has been established and further investigation is required (PMC10521451). More broadly, the systematic review (PMC13163752) identifies higher diabetes-related family conflict as a risk factor for IIO, noting that adolescents who intentionally omit insulin to control weight show higher levels of depression, anxiety, diabetes-related distress, and family conflict compared with peers who do not omit insulin. The diabetes distress meta-synthesis (PMC10691075) found that the Friend/Family Distress subscale of the T1D-DDS was commonly met, with patients describing family members who monitored their diabetes too closely, creating a dynamic that paradoxically increased the psychological burden and potentially reinforced disordered eating as a form of autonomy-seeking.

Social media exposure has been identified as an emerging risk factor, particularly for adolescents. The systematic review (PMC13163752) notes that physical appearance comparisons through social media have been shown to be significantly associated with DSED and dietary restraint, contributing to lower weight satisfaction and representing one of the strongest correlates of dietary restraint in adolescent girls with T1DM.

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### Screening and Assessment

#### The Landscape of Available Tools

The assessment of DEBs in T1DM is complicated by the fact that most general eating disorder screening tools were not designed for individuals with diabetes and do not capture diabetes-specific behaviours such as insulin manipulation. The COVID-19 lockdown study (PMC7708884) explicitly acknowledged that the ChEAT and EAT-26 — widely used general tools — "may fail to identify or inaccurately assess certain diabetes-specific eating behaviors, such as insulin omission or reduction," and that this limitation likely led to underestimation of DEB prevalence in the T1DM group. The editorial (PMC6637645) notes that different screening instruments yield substantially different prevalence estimates, complicating comparisons across studies.

The DEPS-R has emerged as the most widely validated diabetes-specific screening tool, with a recommended cut-off of ≥20 indicating high risk for DEBs and the need for further clinical assessment (PMC9961766, PMC10521451, PMC13163752). It has been applied across multiple languages and populations, including Italian, Arabic, Norwegian, and Ethiopian versions; the Ethiopian version demonstrated acceptable internal consistency (Cronbach's alpha 0.86) (PMC10521451). The DEPS-R includes items specifically addressing insulin manipulation, making it uniquely suited to capture the full spectrum of DEBs in T1DM. The systematic review (PMC13163752) notes that studies using the DEPS-R have reported IIO prevalence rates as high as 60.2% in samples of individuals with T1DM aged 13–55 years, though this figure may be inflated by the inclusion of unintentional omission.

The SCOFF questionnaire — a 5-item general eating disorder screen — has been used as a first-step screening tool in several studies, with a score of ≥2 indicating the need for further assessment (PMC7761849). The Italian exploratory study found significant positive moderate correlations between SCOFF scores and DEPS-R factors 1 ("maladaptive eating habits") and 2 ("preoccupations with thinness and weight") (r = 0.463, p < 0.001 and r = 0.516, p < 0.001, respectively), supporting its utility as an initial screen (PMC7761849). The diabetes distress meta-synthesis (PMC10691075) notes that a modified version of the SCOFF for T1DM (mSCOFF) has been proposed, which replaces the question about weight loss with a question about insulin restriction — a modification that directly captures the diabetes-specific purging behaviour.

The EDE-Q, considered the gold standard screening questionnaire for eating disorders in the general population, has also been applied to T1DM populations. The editorial (PMC6637645) notes that a paper by Keane and colleagues using the EDE-Q reported lower rates of eating disorders than previously reported with other tools, adding to the debate over whether validated general screenings, modified screenings, or T1DM-specific screening tools are the best approach. The qualitative study (PMC7513317) used the EDE-Q to confirm clinical-level eating disorder psychopathology in a sample of individuals with diabulimia, finding a global score of 3.96 (SD = 1.21) comparable to clinical eating disorder samples.

#### Clinimetric Approaches to DEPS-R Interpretation

The Italian exploratory study (PMC7761849) proposed a novel clinimetric approach to DEPS-R interpretation, redistributing its 16 items into four DSM-5-aligned subscales: Restriction and Body Dissatisfaction, Disinhibition, Compensatory Behaviors, and Diabetes Management. The central argument was that the original psychometrically derived DEPS-R subscales may be insufficient for precise clinical classification, and that restructuring items according to DSM-5 criteria could provide more clinically meaningful differentiation. In a sample of 40 youth with T1DM, the newly proposed "Diabetes Management" subscale was the only one showing a significant correlation with HbA1c (r = 0.434, p = 0.006), while the original DEPS-R subscales did not show this association. This finding suggests that a clinimetric reorganisation of the DEPS-R may improve its ability to identify patients at risk of poor glycaemic control specifically due to diabetes management-related eating disturbances.

The study also found that females scored significantly higher than males on the original DEPS-R factor 2 ("preoccupations with thinness or weight"; t(24.62) = −2.408, p = 0.024) and on the newly proposed "restriction" subscale (t(38) = −2.751, p = 0.009), consistent with the broader literature on gender differences in body image concerns. However, the small sample size (n = 40) and the disappearance of all correlations in the high-risk subgroup (DEPS-R ≥ 20, n = 8) limit the interpretability of these findings and call for larger confirmatory studies.

#### Barriers to Detection in Clinical Practice

Despite the availability of validated screening tools, DEBs and IIO remain chronically underdetected in clinical practice. The systematic review (PMC13163752) reports that 65% of patients with IIO have never disclosed the behaviour to their physician, citing shame, stigma, and a perception that healthcare providers focus exclusively on insulin adherence without addressing the underlying psychological distress. Patient accounts from the qualitative literature describe experiences of "misunderstanding, judgment, and perceived lack of provider competence, with a reductionist approach focused exclusively on insulin adherence, failing to address the underlying psychological distress" (PMC13163752). The qualitative study (PMC7513317) found that the majority of participants reported negative experiences with healthcare professionals, with common themes including providers who had never heard of diabulimia or did not understand how difficult it was to stop, and accounts of care that treated T1DM and the eating disorder separately or ignored the eating disorder entirely.

The NHS England pilot service evaluation (PMC12983690) corroborated these findings from the patient perspective: patients described previous care as "disjointed and based on a medical model with the type 1 diabetes and the eating disorder treated separately, or where the eating disorder was largely ignored." Some patients did not recognise they had an eating disorder but had been given the impression that they were a "bad" or "poor" diabetic, resulting in feelings of isolation and disengagement from services. This pattern of clinical misattribution — interpreting IIO as simple non-compliance rather than as a manifestation of eating disorder psychopathology — is a major barrier to timely diagnosis and appropriate treatment.

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### Safety Profile and Adverse Events

#### Acute Complications: Diabetic Ketoacidosis

Diabetic ketoacidosis is the most common acute complication associated with IIO and represents the most frequent reason for medical intervention in this population. The qualitative study (PMC7513317) found that 73% of participants (33/45) had received medical or psychiatric intervention because of their insulin misuse, with the majority describing treatment for DKA on multiple occasions. One participant stated "I've been in DKA more times than I can remember," and another described nearly dying from DKA the previous week. The Saudi Arabian study found that DKA admission in the previous six months was significantly more common in patients with DEBs (16.7%) than in those without (7.8%; p = 0.033) (PMC9961766). The systematic review (PMC13163752) confirms that increased rates of DKA and hospitalisations have been reported particularly among adolescents with IIO and DEBs.

DKA in the context of IIO presents a particular clinical challenge because it may be recurrent and difficult to prevent without addressing the underlying eating disorder. Standard DKA management — which focuses on insulin administration, fluid replacement, and electrolyte correction — does not address the psychological drivers of insulin restriction, meaning that patients are at high risk of re-presenting with DKA after discharge if the eating disorder is not simultaneously treated. The NHS England pilot service evaluation (PMC12983690) noted that staff in T1DE services had to "tolerate high levels of ketones and glucose as part of the treatment initially," reflecting the clinical reality that gradual behavioural change in this population may involve periods of continued metabolic risk.

#### Chronic Complications: Microvascular and Macrovascular Disease

The chronic complications of IIO are extensive and include retinopathy, nephropathy, neuropathy, and cardiovascular disease. The systematic review by Manzoni et al. (PMC13163752) confirms that IIO is associated with an elevated risk of chronic complications, particularly diabetic retinopathy, neuropathy, and nephropathy, with longitudinal studies demonstrating an association between IIO and an increased incidence of microvascular complications, foot-related problems, and mortality. The Ethiopian study (PMC10521451) found that having diabetic complications was associated with more than twice the odds of DEBs (AOR = 2.32, 95% CI: 1.43–3.75), though the cross-sectional design precludes causal inference.

The qualitative study (PMC7513317) provides vivid patient-perspective data on the experience of developing complications: one participant described "my feet hurt, my hair is falling out, my legs are not working like normal. I don't want to be in a wheelchair and bald at 40 so I'm trying to get better." Another participant — a physician — stated "I am a doctor and know all the consequences and even suffer from many of them, neuropathy, nephropathy, but I can't stop." This latter account is particularly striking because it illustrates that awareness of complications is insufficient to motivate behaviour change in the absence of effective psychological treatment, a finding confirmed by the quantitative data showing that 87% of participants in the Coleman et al. study knew how serious the consequences of diabulimia were but found it too difficult to stop (PMC7513317).

#### Severe Hypoglycaemia

While IIO is primarily associated with hyperglycaemia, the Saudi Arabian study found that severe hypoglycaemia was also significantly more prevalent in patients with DEBs (27.8%) than in those without (p < 0.001), and that more frequent admissions due to severe hypoglycaemia were reported in the DEB group (9.7%; p = 0.048) (PMC9961766). This finding may reflect the erratic glycaemic patterns associated with alternating periods of insulin restriction and adequate dosing, or it may reflect the broader dysregulation of diabetes self-management that characterises DEBs. Notably, the diabetes distress meta-synthesis (PMC10691075) found that Hypoglycemia Distress was the least commonly met subscale of the T1D-DDS in individuals with diabulimia — a finding consistent with the systematic review's observation that fear of hypoglycaemia does not appear to play a major role in determining the prevalence of IIO (PMC13163752). This suggests that the hypoglycaemia observed in patients with DEBs is more likely a consequence of erratic insulin management than a feared outcome that drives the behaviour.

#### Mortality

As noted above, endorsing just insulin restriction alone was associated with a 3-fold increase in mortality risk over an 11-year period (PMC6637645). The systematic review (PMC13163752) reports an average reduction in life expectancy of approximately 13 years associated with IIO. In the longitudinal study cited in the systematic review, deceased women exhibited significantly higher HbA1c levels, higher BMI, and more severe eating disorder symptomatology associated with more frequent IIO. These mortality data establish diabulimia as one of the most lethal eating disorder presentations in clinical medicine and underscore the urgency of early detection and effective treatment.

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### Management Strategies and Treatment Evidence

#### The Case for Integrated, Multidisciplinary Care

The consensus across the reviewed literature is that effective management of T1DE requires integrated, multidisciplinary care that simultaneously addresses the metabolic and psychological dimensions of the condition. The editorial (PMC6637645) notes that diabetes specialists report feeling frustrated by the dearth of specialised treatment programmes for eating disorders in people with T1DM, and that T1DM patients with eating disorders are more likely to drop out of conventional outpatient treatment and show worse outcomes with conventional outpatient treatment for eating disorders. Longer stays in residential treatment are reportedly associated with better outcomes, perhaps highlighting greater complexity and need in this population (PMC6637645).

The NHS England pilot service evaluation (PMC12983690) provides the most detailed available evidence on the structure and outcomes of integrated T1DE services. Five new pilot services were evaluated, each employing a multidisciplinary team (MDT) including consultant diabetologists, diabetes specialist nurses, dietitians, psychologists or eating disorder therapists, and in some cases psychiatrists and mental health nurses. Total full-time equivalents ranged from 2.1 to 4.2 across services. Of 198 referrals to the five new pilot services, 150 (76%) completed an initial assessment and 139 (93% of those assessed) were accepted onto the care pathway. After six months of integrated care (n = 47 with follow-up data), HbA1c fell from a mean of 11.2% to 10.2% (a mean reduction of 0.97%), DEPS-R fell from 46.1 to 41.1, and DDS-2 fell from 4.89 to 4.29. Other health outcomes including PHQ-9, GAD-7, and WSAS also showed small positive reductions at six months, though all measures except PHQ-9 remained above clinical thresholds. No significance testing or confidence intervals were calculated for these outcome data, limiting the strength of conclusions that can be drawn (PMC12983690).

The per-patient costs of the T1DE services ranged from £8,147 (Service 4, 51 patients) to £17,074 (Service 5, 24 patients), with total service expenditures ranging from approximately £211,000 to £415,000 through to mid-2025 (PMC12983690). The authors note that costs are likely to reduce once services become fully embedded and patient throughput increases. A previous evaluation of two earlier NHS England T1DE pilot services reported statistically significant reductions in HbA1c of 2.3% (range: reduction of 7.1% to increase of 0.4%, n = 11) and 2.5% (range: reduction of 8.9% to increase of 2.4%, n = 14) after 12 months of follow-up, with improvements in other health outcomes including diabetes disordered eating, depression, and anxiety (PMC12983690). More recently published data for the London T1DE service on 47 patients with 12-month follow-up showed a statistically significant reduction in HbA1c of 0.92% (95% CI 0.31 to 1.54, p = 0.0047), with reductions also seen in DEPS-R, PHQ-9, and GAD-7 (PMC12983690).

#### Psychological Treatment Approaches

The qualitative literature consistently identifies psychological intervention as the cornerstone of effective treatment for diabulimia. The qualitative study (PMC7513317) found that 87% of participants knew how serious the consequences of diabulimia were but found it too difficult to stop, confirming that education about complications alone is insufficient and that effective psychological treatment must follow any diabetes education. Participants described the benefits of psychological support including "Acceptance of my body through DBT" (dialectical behaviour therapy), and expressed a need for "psychological support from diagnosis all the way through."

The diabetes distress meta-synthesis (PMC10691075) proposes a multidisciplinary treatment framework informed by the DD model. For the diabetes management team, the authors recommend emphasising "good enough" glycaemic control over "optimal," and note that decreasing time spent on diabetes self-management can decrease diabetes distress and play a role in diabulimia recovery. For the dietitian team, goals should include re-establishing a regular meal pattern, establishing intuitive approaches to meal planning, and potentially relaxing carbohydrate counting. Providers should avoid giving positive reinforcement for any weight loss that occurs during recovery. For the mental health team, cognitive behavioural therapy (CBT) and assessment of the impacts of T1DM and the eating disorder on daily living are recommended. The authors also note that online group seminars addressing the facts of diabetes diet and management have been found to be as efficacious in reducing DD and HbA1c as online group meetings discussing the emotional aspects of diabetes management, though those with poor emotion regulation or poor cognitive skills benefited most from the emotion-focused intervention (PMC10691075).

The systematic review (PMC13163752) identifies several specific therapeutic targets informed by the psychological mechanisms of IIO: pre-meal anxiety and guilt, rigid and punitive approaches to food and diabetes management, diabetes distress, and the dysfunctional belief that "insulin = weight gain." The review recommends "in-the-moment" interventions targeting the acute emotional states that precede IIO — including anxiety, nervousness, guilt, self-disgust, sadness, anger, and frustration — rather than exclusively generic therapies. Psychological support targeting trauma and maladaptive beliefs about weight and appearance is identified as particularly important, given the high prevalence of trauma histories in this population (PMC7513317, PMC13163752).

The NHS England pilot service evaluation (PMC12983690) found that patients valued the ability to choose options they felt they would benefit from (talking therapy, dietetic advice, diabetes advice), services that worked at a pace to suit them, and practical tips and advice. Patients described how services were quick to respond via email and phone, and appreciated the flexibility of face-to-face or online appointments. Staff reported that the integrated T1DE team enabled better targeted care by treating T1DE as a single entity rather than treating disorders separately. The importance of peer support and clinical supervision for staff was highlighted as essential for managing the emotional toll of working with this high-risk group.

#### Screening and Early Detection in Clinical Practice

The systematic review (PMC13163752) recommends that both eating disorders and IIO should be assessed during the initial clinical evaluation of all patients with T1DM, with regular screening thereafter. The introduction of simple screening questions into routine clinical practice — such as "I take less insulin than I should" — may facilitate the early identification of at-risk individuals and their referral to specialist support. Routine screening for eating disorders should be particularly emphasised among individuals with elevated BMI and persistently high HbA1c levels. The diabetes distress meta-synthesis (PMC10691075) recommends that clinicians consider utilising the PAID scale or DDS to evaluate for the presence of underlying DD as a driver for disordered eating behaviours, and that routine DD screening in every patient with T1DM could one day be a vital tool for prevention and early intervention.

The Italian exploratory study (PMC7761849) suggests that a two-step screening approach — using the SCOFF as a first-step screen followed by the DEPS-R for those who screen positive — may be useful in clinical settings. The proposed DSM-5-aligned subscales of the DEPS-R may provide additional clinical value in characterising the specific pattern of DEBs in patients who screen positive, though this approach requires validation in larger samples. The Saudi Arabian study (PMC9961766) concludes that "routine screening for DEBs should be an essential element of diabetes care, especially in adolescents and young adults," and that the observed association between DEBs, BMI, high HbA1c, and more frequent DKA or severe hypoglycaemia should raise physician awareness about the need for systematic screening.

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### Unresolved Controversies and Disagreements

#### The Diagnostic Status of Diabulimia

Perhaps the most fundamental unresolved controversy in this field concerns the diagnostic status of diabulimia. The condition lacks formal recognition in either the DSM-5 or ICD-11, and is classified only loosely under "drug abuse to ensure undefined eating disorder/weight loss" in the DSM-5 framework (PMC13163752). The systematic review (PMC13163752) argues that IIO should be conceptualised not merely as a weight-control strategy but within the broader framework of eating disorder psychopathology, and that the absence of formal diagnostic recognition continues to limit early identification and the development of structured care pathways. The qualitative study (PMC7513317) notes that the omission of the label "diabulimia" in most research is likely because many researchers use formal diagnostic categories, while individuals identify with the term and may use it with healthcare professionals.

The term "diabulimia" itself is contested. The systematic review (PMC13163752) notes that the term is pseudo-Greek and etymologically imprecise — "diabulimia has nothing to do with bulimic behaviour; rather, it is related to a restrictive style of eating" — and prefers the more precise term "intentional insulin omission" (IIO). However, the term "diabulimia" has gained significant traction in patient communities, advocacy organisations, and media coverage (including a 2017 BBC documentary titled "Diabulimia: The World's Most Dangerous Eating Disorder"), and its use by patients in clinical encounters may facilitate communication about the behaviour. The tension between clinical precision and patient-centred language remains unresolved.

#### Gender Differences: Real or Artefactual?

A second major controversy concerns the magnitude and consistency of gender differences in IIO prevalence. The systematic review (PMC13163752) explicitly states that "the purported higher prevalence of IIO in female patients with T1D is not confirmed by several studies," and that "the fact that some studies were limited to female patients renders the observed gender differences unreliable." A meta-analysis cited in the review showed a higher prevalence in female patients with T1DM, but the authors caution that this result may be artefactual given the female-only design of many included studies.

In contrast, the Saudi Arabian study (PMC9961766) found a significantly higher DEB prevalence in females (32.5%) than males (18.6%; p = 0.01), while finding no significant gender difference in insulin restriction or omission specifically. The Ethiopian study (PMC10521451) found similar DEB prevalence in females (21.8%) and males (21.5%), with no significant difference in DEPS-R scores. The COVID-19 lockdown study (PMC7708884) found significant main effects of gender on all ChEAT/EAT-26 subscales (girls scoring higher than boys), but no significant interaction between gender and T1DM status. The qualitative study (PMC7513317) was almost entirely female (42/45), reflecting both genuine female predominance in help-seeking and the methodological challenge of recruiting male participants. The NHS England pilot service evaluation (PMC12983690) reported that 89% of patients accepted onto the T1DE care pathway were female, but acknowledged that one study has suggested insulin restriction or omission may be just as prevalent among males.

The resolution of this controversy has important clinical implications: if IIO is as prevalent in males as in females, then current screening practices — which may be implicitly or explicitly biased toward female patients — are missing a substantial proportion of affected individuals. Future research using population-based sampling and gender-inclusive recruitment strategies is needed to resolve this question.

#### Prevalence Estimates: The Role of Assessment Methodology

A third major controversy concerns the wide variation in DEB and IIO prevalence estimates across studies, which ranges from 8.69% to 59% for DEBs and from 7.6% to 60.2% for IIO (PMC10521451, PMC13163752). The editorial (PMC6637645) explicitly notes that "different screening methods produce different results regarding rates of eating disorders in this population," and that a paper by Keane and colleagues using the EDE-Q reported lower rates than previously reported with other tools. The COVID-19 lockdown study (PMC7708884) found no significant difference in DEB frequency between T1DM youth and healthy controls using the ChEAT/EAT-26, but explicitly acknowledged that these tools do not capture insulin manipulation and likely underestimate DEB prevalence in the T1DM group.

The systematic review (PMC13163752) notes that prevalence estimates are further complicated by the fact that some studies include unintentional or involuntary insulin omission among cases, inflating the prevalence rate. The Saudi Arabian study (PMC9961766) acknowledges that the two DEPS-R questions concerning insulin restriction and omission "do not specify that the reason for such behavior is for the purpose of weight loss," meaning that other causes of insulin reduction — including injection anxiety, fear of hypoglycaemia, interference with daily living activities, or diabetes burnout — cannot be excluded. This methodological limitation means that published IIO prevalence figures likely overestimate the proportion of patients engaging in IIO specifically for weight control purposes.

#### The Bidirectional Relationship Between DEBs and Glycaemic Control

A fourth area of controversy concerns the directionality of the relationship between DEBs and glycaemic control. The systematic review (PMC13163752) describes a bidirectional relationship: the presence of DEBs is associated with poorer glycaemic control (higher HbA1c), while elevated HbA1c levels appear to promote DEBs, "likely mediated by psychological and behavioural mechanisms related to distress, frustration, and the burden of daily disease management." This reciprocal interaction may contribute to a vicious cycle in which poor glycaemic control and DEBs mutually reinforce each other. However, the cross-sectional design of most studies in this field precludes definitive conclusions about the temporal sequence of this relationship, and the longitudinal evidence is limited to a small number of studies with methodological limitations.

The Ethiopian study (PMC10521451) found that having diabetic complications was associated with more than twice the odds of DEBs (AOR = 2.32, 95% CI: 1.43–3.75), but explicitly acknowledged that "it might not be possible to describe whether a change in BMI is preceded by engagement in DEBs and vice-versa." The systematic review (PMC13163752) notes that IIO has been shown to be a stronger predictor of poor metabolic control than other compensatory behaviours, including binge eating and purging, suggesting that the specific mechanism of insulin restriction — rather than disordered eating per se — is the primary driver of glycaemic deterioration.

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### Limitations of the Evidence Base

The evidence base for eating disorders concurrent with T1DM, and for diabulimia specifically, is characterised by several important methodological limitations that constrain the strength of conclusions that can be drawn.

The predominance of cross-sectional study designs across the reviewed literature is the most fundamental limitation, as it precludes causal inference about the relationships between DEBs, IIO, glycaemic control, and clinical outcomes. The systematic review (PMC13163752) identified 25 cross-sectional and 4 longitudinal studies among the 29 eligible studies. The cross-sectional design is particularly problematic for understanding the temporal sequence of the relationship between DEBs and diabetic complications, and for evaluating the effectiveness of treatment interventions.

Marked methodological heterogeneity across studies — including variability in assessment instruments, population definitions, age ranges, and inclusion of unintentional insulin omission — complicates prevalence estimation and cross-study comparability. The use of non-diabetes-specific screening tools (EAT-26, ChEAT, SCOFF, EDE-Q) in many studies likely leads to systematic underestimation of DEB prevalence in T1DM populations by failing to capture insulin manipulation. Conversely, some studies using the DEPS-R may overestimate IIO prevalence by including unintentional omission or omission motivated by factors other than weight control.

The absence of validated diagnostic criteria for diabulimia in major classification systems (DSM-5, ICD-11) hampers research standardisation and makes it difficult to compare findings across studies that use different operational definitions of the condition. The systematic review (PMC13163752) identifies this as a major obstacle to the development of structured therapeutic pathways and calls for shared diagnostic criteria as a research priority.

Low- and middle-income countries are substantially underrepresented in the available literature, limiting the generalisability of findings to diverse cultural and healthcare contexts. The Ethiopian study (PMC10521451) represents a valuable exception, but its findings — including a DEB prevalence of 43.3% and a pattern of predominantly non-purging behaviours — suggest that the clinical presentation of DEBs in T1DM may differ substantially across cultural contexts.

The predominantly female samples in most studies limit generalisability to male patients, who are known to underreport eating disorder symptoms and are less likely to participate in eating disorder research. The qualitative study (PMC7513317) obtained only two male responses, and the NHS England pilot service evaluation (PMC12983690) reported that 89% of patients accepted onto the T1DE care pathway were female. The systematic review (PMC13163752) explicitly flags that gender comparisons are unreliable because many studies enrolled exclusively female samples.

The reliance on self-report measures for both IIO and eating disorder symptoms introduces potential underestimation due to shame and stigma. The systematic review (PMC13163752) notes that 65% of patients report never having disclosed IIO to their physician, suggesting that self-report data collected in clinical settings may substantially underestimate the true prevalence of the behaviour. The qualitative study (PMC7513317) acknowledged that "due to the reliance on self-report data, it is possible that participants had a wide range of insulin restriction severity and frequency," and that selection bias may have led to over-representation of individuals with more severe insulin misuse.

The NHS England pilot service evaluation (PMC12983690) is limited by small patient numbers (47 with six-month follow-up data), the absence of a control or comparator group, and the predominantly female, white/white British patient sample. The evaluation was conducted during an early implementation phase when services were not yet fully operational, and two of the three original pilot services closed during the evaluation period due to funding uncertainty, raising serious questions about the sustainability of the integrated care model in its current form. The absence of significance testing or confidence intervals for the outcome data further limits the strength of conclusions about clinical effectiveness.

The Italian exploratory study (PMC7761849) is limited by a very small sample size (n = 40), a single-centre design, and the absence of a clinical interview or DSM-5 diagnostic confirmation as a gold standard. The COVID-19 lockdown study (PMC7708884) is limited by the use of non-diabetes-specific assessment tools, voluntary online participation with parent-reported anthropometric and glycaemic values, and the restriction to patients using a specific CGM device (FreeStyle Libre), which excluded 403 of 751 eligible patients and likely selected a more adherent or closely monitored subgroup.

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### Special Populations

#### Adolescents and Young Adults

Adolescents and young adults represent the highest-risk group for the development of DEBs and IIO in T1DM, and the evidence base is most developed for this population. The systematic review (PMC13163752) identifies adolescence as a particularly critical developmental period for the onset of DEBs, noting that the prevalence of DEBs increases among girls between 17 and 19 years of age and is further elevated in the presence of weight gain. The Ethiopian study (PMC10521451) found that late adolescence was associated with approximately twice the odds of DEBs compared to early adolescence (AOR = 2.10, 95% CI: 1.33–3.34). The Saudi Arabian study (PMC9961766) found no significant difference in DEB prevalence between adolescents (27.7%) and young adults (26.3%), suggesting that the elevated risk established in adolescence persists into young adulthood.

The transition from parental to self-management of insulin administration during adolescence is identified as a particularly vulnerable period (PMC6637645). The systematic review (PMC13163752) notes that adolescence involves major physical, hormonal, and psycho-emotional changes that hinder optimal disease management, and that additional risk factors during this period include family conflict, negative body image perception, psychological distress, and increasing autonomy. The COVID-19 lockdown study (PMC7708884) found that age was a significant predictor of DEB symptoms in both T1DM and control groups, with adolescents showing higher levels of dieting behaviours but lower oral control than children.

#### Low- and Middle-Income Country Populations

The Ethiopian study (PMC10521451) provides the most detailed evidence on DEBs in T1DM in a low-income country context. The overall DEB prevalence of 43.3% is among the highest reported in the literature, and the pattern of predominantly non-purging behaviours (alternating meals: 46.6%; avoiding blood sugar checks: 26.6%) differs from the pattern seen in Western samples, where purging behaviours including IIO are more commonly reported. The authors note that the DEPS-R had not been formally validated in the Ethiopian context, though face validity was assessed via focus group discussions and the tool's Cronbach's alpha was acceptable (0.86). The predominantly urban (93.4%) sample limits generalisability to rural populations within Ethiopia.

The Indian cross-sectional study (PMC10870338) examined EDs in adults with T2DM rather than T1DM, finding that 35% of participants were at high risk of developing an ED per SCOFF criteria, with males showing higher ED risk than females — a finding that diverges from most of the existing literature. Education level was the only statistically significant predictor of EDs in logistic regression (OR = 1.47, 95% CI 1.00–2.16, p = 0.04), with each one-unit increase in education associated with approximately 47% higher odds of having an ED. While this study is not directly applicable to the T1DM/diabulimia question, it highlights the importance of studying EDs in diabetes across diverse cultural and socioeconomic contexts.

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### Conclusions and Future Directions

The evidence synthesised in this review supports several clear conclusions. First, eating disorders and disordered eating behaviours are substantially more prevalent in individuals with T1DM than in the general population, with a relative risk of approximately 2.5 for any eating disorder and DEB prevalence estimates ranging from 20% to 45% across populations. Second, intentional insulin omission for weight loss — diabulimia — is a common, dangerous, and chronically underrecognised behaviour that is associated with a threefold increase in mortality risk, an average reduction in life expectancy of approximately 13 years, and substantially elevated rates of DKA, microvascular complications, and hospitalisation. Third, the psychological mechanisms driving IIO are complex and multifactorial, encompassing fear of weight gain, emotion dysregulation, body image disturbance, diabetes distress, and in some cases self-harm — and cannot be addressed through diabetes education alone. Fourth, integrated, multidisciplinary care that simultaneously addresses the metabolic and psychological dimensions of T1DE is feasible, broadly acceptable to staff and patients, and associated with modest improvements in glycaemic and psychological outcomes over six months, though the evidence base for clinical and cost-effectiveness remains limited.

The evidence does NOT support several commonly held assumptions. The assumption that IIO is exclusively or predominantly a female problem is not supported by several recent studies showing similar prevalence in males and females, and is likely artefactual given the female-only design of many earlier studies. The assumption that awareness of complications is sufficient to motivate behaviour change is directly contradicted by the finding that 87% of individuals with diabulimia knew how serious the consequences were but found it too difficult to stop. The assumption that standard outpatient eating disorder treatment is adequate for this population is contradicted by evidence that T1DM patients with eating disorders are more likely to drop out of conventional outpatient treatment and show worse outcomes. The assumption that diabulimia is a condition of high-income, Western societies is challenged by the Ethiopian study reporting a DEB prevalence of 43.3% in a low-income country context.

Several important open questions and future research priorities emerge from this synthesis. First, the development of shared, validated diagnostic criteria for diabulimia — potentially as a distinct category in future editions of the DSM and ICD — is urgently needed to standardise research and clinical practice. The current classification of IIO under "drug abuse to ensure undefined eating disorder/weight loss" in the DSM-5 is inadequate and fails to capture the clinical complexity of the condition. Second, large-scale, population-based longitudinal studies are needed to establish the true prevalence of IIO in both male and female patients with T1DM, to characterise the natural history of the condition from onset to resolution or complication, and to identify the most effective windows for preventive intervention. Third, randomised controlled trials of specific psychological interventions for diabulimia — including CBT adapted for T1DM, dialectical behaviour therapy, acceptance and commitment therapy, and trauma-focused approaches — are critically needed, as the current evidence base for treatment is almost entirely observational. Fourth, the role of gut microbiota alterations as biological biomarkers of IIO and DEBs warrants further investigation, with the potential to develop objective screening tools that complement self-report measures. Fifth, the development and validation of HbA1c trajectory algorithms and machine learning approaches for the early identification of IIO — as proposed by Pinhas-Hamiel and colleagues and cited in the systematic review (PMC13163752) — represents a promising avenue for improving detection in clinical practice. Sixth, research on the cost-effectiveness of integrated T1DE services is urgently needed to support commissioning decisions, with longer-term outcome data including hospital admissions, DKA episodes, and A&E attendances being particularly important. Seventh, studies specifically designed to recruit and retain male participants with IIO are needed to resolve the controversy about gender differences in prevalence and to ensure that clinical screening practices are not inadvertently biased toward female patients. Finally, the development of culturally adapted screening tools and treatment approaches for low- and middle-income country populations — where the burden of T1DM is growing rapidly and the evidence base is almost entirely absent — represents a major global health priority.

In summary, diabulimia represents a complex, hybrid clinical condition at the intersection of metabolic disease and eating disorder psychopathology that cannot be reduced to simple treatment non-compliance. Its management requires close collaboration between diabetes services and mental health services, with clinical attention focused on eating disorder psychopathology, body image disturbances, difficulties in accepting diabetes, and the possible role of trauma and self-harming processes. The absence of formal diagnostic recognition continues to limit early identification and the development of structured care pathways. Recognising diabulimia as a distinct, high-risk clinical entity — and investing in the integrated, multidisciplinary services needed to address it — is essential to improving detection, treatment, and long-term outcomes for one of the most vulnerable and underserved populations in contemporary medicine.

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*Competing interests: None declared. Funding: None. This review was conducted as a narrative synthesis of the provided literature and does not represent a registered systematic review.*

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