Type 1 diabetes mellitus and disordered eating

‘T1DE’ refers to a range of disordered eating presentations in people with type 1 diabetes mellitus (T1DM) who use insulin restriction and a range of other behaviours to control their weight. 

T1DM is an autoimmune condition characterised by the complete cessation of insulin production in the body, resulting in a lifelong requirement to self-monitor blood glucose levels (by finger-prick blood glucose test or continuous glucose monitor)^​1​. It requires people with diabetes to predict and control blood glucose levels through insulin adjustment with multiple daily injections or the operation of an insulin pump^​1​.

Around 400,000 people in the UK are estimated to have T1DM, which accounts for around 8% of diabetes cases; there is a peak incidence in childhood^​2,3​.

Diabulimia is a term often used in the media to describe when a person with T1DM has an eating disorder, but the name implies a link with bulimia nervosa, which is not necessarily the case. In medical literature, the term ‘T1DE’ is commonly used because it better acknowledges that disordered eating behaviours can manifest in several ways, such as dietary restriction, binge eating or insulin restriction^​4​.

Eating disorders have one of the highest mortality and suicidality rates of any mental illness and they are nearly twice as common in T1DM than in the general population^​5–7​. Uniquely, people with T1DM can restrict or omit insulin to reduce or avoid gaining weight, which is one of the main features of disordered eating in T1DM. Estimates of prevalence vary, but one study (n=234) reported that 30% of participants restricted insulin^​8,9​.

NHS England has trialled a joined-up treatment pathway between diabetes and eating disorders services in each region in England. This integrated approach has been shown to be cost effective and improve clinical outcomes^​10,11​. A sample of patients under the King’s College Hospital T1DE service (n=78) experienced a reduction in HbA1c, reduced hospital admissions for diabetic ketoacidosis (DKA), and a reduction in severe hypoglycaemic episodes over a 12-month period^​11​. 

There is a lack of equity of access to T1DE pilot services nationally. The majority of people with T1DE in the UK continue to be managed separately in diabetes and eating disorders services, without the cross supervision that is necessary for safe management of high risk T1DE. A 2024 parliamentary inquiry highlighted the risks to people with T1DE and recommended funding for specialist T1DE services, as well as a consensus on diagnostic criteria and a clinically approved pathway for prevention and treatment^​12​.

Early identification and intervention for eating disorders is strongly advocated in national guidance and can lead to more positive treatment outcomes^​12,13​. As a result, it is recommended that pharmacists in contact with people with T1DM are alert to potential signs and symptoms of T1DE (see below).

This article will provide an overview of the risks associated with T1DE and describe how the condition can be identified and managed, including communication considerations for healthcare professionals.

Causes and risk factors

When people with T1DM become insulin deficient prior to their diabetes diagnosis or from insulin omission, the subsequent hyperglycaemia, polyuria and osmotic diuresis results in a catabolic and dehydrated state, resulting in rapid weight loss. In these cases, people are rapidly re-insulinised, which can cause rapid weight gain and oedema, establishing the negative belief that insulin causes weight gain and promoting a recurring cycle of insulin omission^{​7,11,14​}.

Intensive diabetes management for T1DM, which features carbohydrate counting and insulin dose adjustment, has a robust evidence base for improving HbA1c^​14​. However, it carries an increased risk of weight gain that can be difficult to lose long term^​15,16​. Some of the main features of diabetes management, such as checking nutrition labels, measuring portion sizes, encouraging exercise and weighing people, can mirror the eating disorder mindset^​16​.

Risks and mortality in T1DE

People with T1DE have a three-fold mortality risk compared with those with T1DM who do not experience disordered eating^​8​. Insulin restriction results in increased levels of blood glucose and ketone levels, which exposes the individual to significant acute risk of DKA, resulting in more frequent hospital admissions and longer stays^​8,17​.

More information about DKA can be found in ‘Diabetic ketoacidosis in adults: identification, diagnosis and management’. Insulin restriction will also make a person more susceptible to accelerated long-term complications of diabetes, such as nephropathy, foot problems and retinopathy^​18​.

Many of the physical and psychological risks associated with low weight and starvation in T1DE mirror those in individuals with eating disorders without T1DM^​19​.

For example, cognitive effects may include impaired concentration, memory and decision-making, as well as increased cognitive rigidity and anxiety. People with eating disorders may also have co-existing mental health difficulties, such as low mood or anxiety. Physiological effects may include dehydration, low blood pressure, an increased risk of refeeding complications and early reductions in bone mineral density^​19​.

Living with T1DM comes with a significant ‘diabetes burden’ stemming from the innumerable self-management activities and psychological impact. It significantly increases the prevalence of mental health conditions, such as anxiety and depression, which can exacerbate disordered eating behaviours^​20,21​.

Identification and diagnosis

Proposed diagnostic criteria

There is currently no formal consensus on T1DE diagnostic criteria as classified in either the World Health Organization’s International Classification of Diseases 11th revision (ICD-11) or the American Psychiatric Association’s Diagnostic and Statistical Manual of Mental Disorders 5th edition (DSM-5)^​2,3​. This poses a challenge for accurate identification and diagnosis of T1DE and its varying presentations.

Where there is cause to suspect T1DE, healthcare professionals may choose to use proposed diagnostic criteria for T1DE published by the Royal College of Psychiatrists to help differentiate it from other potential diagnoses; however, a formal diagnosis can only be made through a clinical assessment by a psychiatrist or eating disorder multidisciplinary team (see Box 1^​19​).

Red flags and barriers to detection

Detection of T1DE can be challenging. Eating disorders are unlikely to be self-reported, and people with T1DE may disguise their difficulties owing to feelings of shame and fear of judgement from HCPs, family and friends, which may be rooted in past adverse experiences with diabetes-related healthcare delivery^​13,22​. T1DE can be mistaken for other drivers of insulin restriction, such as a dislike of needles, fear of hypoglycaemia, or behaviours related to diabetes burnout or depression. However, T1DE is underpinned by intense weight and shape concerns, which sets it apart from these other causes of insulin restriction^​19​.

There are many ways to manipulate how much active insulin is on board. For example, deliberate deterioration of insulin through heat exposure, reducing absorption into the body by injecting into areas of lipoatrophy, or incorrectly siting a pump cannula. Some may falsify blood glucose readings or carbohydrate intake to mislead bolus advisors/pumps into recommending smaller insulin doses than required^​22​. Insulin over-injection has also been observed, either as a response to binge eating or out of fear that high blood glucose may lead to long-term complications of diabetes^​22​. A range of additional strategies may be employed to raise blood glucose, such as overconsumption of carbohydrate or sugary foods, including hypoglycaemia treatments. In a person without enough circulating insulin, exercise will also raise blood glucose levels and increase ketone production^​22​.

Early identification and intervention for eating disorders is strongly advocated in national guidance and can lead to more positive treatment outcomes; therefore, it is recommended that pharmacists in contact with people with T1DM are alert to potential signs and symptoms of T1DE, which will vary from person to person^​12,13​ (see Box 2^​19​).

When pharmacists identify someone with red flags for T1DE, they should liaise with the diabetes team to discuss the concerns, even if a T1DE diagnosis is uncertain.

Healthcare professionals need to be vigilant when assessing the reasons for variable glycaemic control and weight changes; however, the majority of people with T1DE are of a normal weight, with a BMI of 18.5–25kg/m² in adults, or above 85% mBMI in children and young people^​19​. The complications and mortality risks from insulin omission can occur at any weight, it is important for pharmacists to be aware that BMI should not be used to exclude a diagnosis of an eating disorder in T1DM^​19​. This information should be communicated to eating disorders services at the point of referral, as these services traditionally use low BMI in referral criteria.

Similarly, not everyone with T1DE will present with a high HbA1c2. Some individuals with disordered eating restrict carbohydrate or total energy intake in their diet with matched insulin doses, resulting in a lower HbA1c. This is referred to as indirect restriction of insulin^​19​. These behaviours can result in a higher risk of weight loss, low BMI and symptoms of malnutrition. When HbA1c is in-range, healthcare professionals may not suspect T1DE and may even praise the in-range HbA1c, affirming the person’s disordered eating behaviours. 

Hypoglycaemia

Some individuals with T1DE may take more insulin than needed; for example, owing to a drive to control glucose, as a rescue dose in response to hyperglycaemia to avoid DKA, or in response to a binge. Pharmacists should be aware that individuals with T1DE can experience the full range of nocturnal, recurrent and severe hypoglycaemia, and they can have hypoglycaemia unawareness, which is exacerbated when they skip or delay hypoglycaemia treatments.  

Low carbohydrate/low calorie diets can result in depleted liver glycogen stores and therefore glucagon injections should not be recommended as there is a risk they will not be effective in resolving hypoglycaemia^​19​. 

Screening for T1DE

Most routine screening tools for eating disorders are not valid in T1DM because self-management requires an intense focus on food to manage blood glucose levels; therefore, these tools have the potential to overestimate eating difficulties in T1DM^​23​.

Pharmacists reviewing adults with possible T1DE could consider utilising a validated screening tool, such as the Diabetes Eating Problem Survey-Revised (DEPS-R) or the mSCOFF questionnaire adapted for T1D populations^​24,25​. It may be useful to identify which items the individual highlights as a problem to help guide conversations and to use in onward referrals.

Although screening tools can form a useful part of the clinical picture, particularly when used by a dedicated T1DE service, they can be a challenge to incorporate into busy clinics and clinicians may not feel they have the skills to approach this area of conversation^​26​. They cannot be used in isolation to diagnose an eating disorder and should be interpreted with the full psychosocial and physical health picture by a consultant psychiatrist and/or with an eating disorders multidisciplinary team. 

Communication skills 

When interacting with people with T1DM, it is crucial to remain aware of potential for disordered eating. Each conversation with a healthcare professional can count; the process of engaging someone with T1DE can start during a routine appointment and may provide the first opportunity for them to be listened to. While healthcare professionals may not feel confident or skilled in this area to initiate a discussion, eating disorders are often kept secret owing to guilt and shame and can be easily missed or misinterpreted as diabetes burnout, fear of hypoglycaemia or other difficulties^{​13,26,27​}.

More information can be seen in Box 3.

Management

There is not a standardised pathway for the management of T1DE and several factors have historically resulted in the exclusion of people with T1DE from the support and expert treatment that they require. Current national guidance recommends a joint diabetes and eating disorders approach to treatment^​19​, but there is a lack of equitable funding (see Box 4). 

Referral criteria for eating disorder services can traditionally be shaped by anorexia nervosa criteria, such as a low BMI, which may not be a feature of T1DE, and may exclude this group from eating disorder services.  

A specialist T1DE outpatient multidisciplinary team varies depending on the availability and expertise of healthcare professional, but evidence from the pilots suggest it should involve a combination of diabetes and eating disorder/mental health professional who each have the knowledge, skills and experience to manage T1DE^​10,11​. This shared care model should involve collaboration with the people who have diabetes and their families.

Therapeutic interventions

There is an emerging but limited evidence base regarding the psychological therapies that are effective in treating eating disorders in T1DM^​30​. NICE guidance highlights the opportunity to investigate the efficacy of modified eating disorders therapy for people with a long-term condition^​13​.

In the NHS England T1DE pilots, psychological interventions have drawn upon the evidence base and recommendations for eating disorders, in combination with the psychological difficulties associated with living with diabetes, including diabetes distress and fear of hypoglycaemia ^​4,19​.  This includes, but is not limited to, enhanced cognitive behavioural therapy (CBT-E) for eating disorders, trauma therapy, compassion-focused therapy, psychodynamic therapy and family-based therapy (in children’s services)^​13,31​.

CBT-E is designed to treat anorexia nervosa, which is usually focused on weight restoration, has been successful when adapted to account for diabetes-specific influence on psychopathology and the physical risks from managing insulin restriction. This requires the psychological practitioner to have knowledge and experience from both specialties^​4,19​. 

Some traditional eating disorder models — such as the ‘Maudsley anorexia nervosa treatment for adults’ (MANTRA)^​13​ — may offer limited, outdated dietary advice for individuals with T1DE, and is likely to be delivered by a healthcare professional without diabetes-specific knowledge or input from physical health specialists. Practical, psychological interventions should ideally be delivered by a psychological professional jointly or concurrently with a diabetes specialist to bring aspects of both conditions into the therapy and facilitate learning between the specialists. They should also complement the other interventions offered, such as dietetic management^​4,19​. 

A patient’s family has a crucial role in prevention and supporting recovery of T1DE in children. Evidence from the ‘PRIORITY’ trial has highlighted that family-based interventions, particularly those involving psycho-education for parents, can be instrumental in preventing disordered eating in young people with T1DM^​32​. This approach equips parents to recognise early signs of disordered eating, challenge food-related anxieties and foster more flexible, value-based approaches to eating^​32​.

In addition to formal psychological therapies offered, there should be an overarching psychological approach to all interactions between members of the healthcare team and patient, focusing on:

• Building engagement; 
• To hold empathy and validate the emotions of the patient;
• Developing realistic expectations and working at the individual’s pace; 
• Noticing progress and celebrating success.

Peer support is also thought to have an important place in the recovery journey of someone with T1DE (see ‘Useful resources’)^​33​.

Insulin management

When reintroducing or titrating insulin to safe levels in people who restrict or omit insulin, guiding principles should prioritise patient safety and the prevention of DKA.33 Rather than aiming for rapid normalisation of glucose levels — which can be unrealistic and may increase the risk of hypoglycaemia, treatment-induced neuropathy or worsening retinopathy — a stepped, harm-reduction approach is recommended. This gradual pace can support greater psychological tolerance to changes in insulin and glucose, ultimately moving towards recommended targets. Everyone with T1DM will have glucose levels outside the target range at times and this approach can help to reduce shame and perfectionistic thinking. However, healthcare professionals may find it difficult to tolerate the anxiety associated with a person with T1DE having high glucose or ketone levels, which further underscores the importance of shared decision-making and effective clinical supervision^​34​.

Community pharmacists could be well placed to pick up on failure to request regular prescriptions for insulin when compared to prescribed doses, which should then be documented and communicated to the GP or the relevant diabetes consultant.

In the inpatient setting, specialist hospital pharmacists can support their ward/specialist teams with managing patients with T1DE by:

• Providing advice around safe insulin storage; 
• In conjunction with the diabetes team, ensuring guidance around self-management of insulin is available for inpatients to support a patient with T1DE as they recover and move more to self-managed care. 

Technology in T1DE 

People living with T1DE should have equal access to diabetes technology, and discussions should be had regarding the individual pros and cons, with their wishes taken into consideration. Its use in T1DE requires careful consideration. The two main technologies are continuous glucose monitoring (CGM) and insulin pumps/hybrid closed loop systems (HCL).

Benefits and challenges of diabetes technology are summarised in the Figure below^​35​.

For healthcare professionals supporting patients with T1DE, technology decisions require careful individualisation and ongoing monitoring. Sharing of CGM data should be requested rather than assumed. Data patterns may provide important indicators of psychological distress and eating disorder behaviours. While setting realistic expectations outside standard parameters is essential, it is important to maintain hope for recovery.

HCL systems might be more appropriate during recovery phases, with clear protocols established for both implementation and discontinuation. Throughout treatment, maintaining a balance between utilising technology’s benefits while managing its psychological impact remains crucial for optimal patient care.

Nutritional considerations in T1DE

Dietetic assessment may highlight compensatory strategies in addition to insulin restriction, for example:

• Restriction of total energy or selective restriction of carbohydrate intake;
• Unrestricted eating of carbohydrate in a deliberate attempt to keep blood glucose and ketones raised to achieve weight loss;
• Over-exercise patterns and purging behaviours (including self-induced vomiting, laxative misuse, diuretic use and excessive exercise);
• Technology manipulation (such as underreporting carbohydrates in pump settings).

Once any risks associated with refeeding have been managed, dietary counselling should be aimed to work with the person with diabetes to gradually move towards a normalised pattern of balanced eating in line with mainstream recommendations for T1DM. This requires a stepped approach, with acceptance that perfect glycaemic control is not an early treatment goal.

Various dietary patterns can be appropriate (Mediterranean, plant-based, low GI) if implemented non-restrictively, while restrictive approaches, such as low carbohydrate or ketogenic diets, pose particular risks for this vulnerable group. It is ideal to include a wide variety of foods, including moderate amounts of sugar-containing foods, to avoid reinforcing restrictive eating patterns.

Experience from NHS pilot sites has found that it may benefit some people with T1DE to temporarily leave aside carbohydrate counting and take up a more generalised dietary approach alongside fixed doses of insulin. This can help reduce the focus on numbers and detailed food monitoring that might maintain disordered eating patterns.

Weight gain associated with improved glucose control and reinsulinisation should be anticipated and addressed sensitively as part of treatment planning. This is commonly experienced at diagnosis, following DKA admissions, and in those new to hybrid closed loop systems. 

Small, achievable steps in dietary change are preferred over rapid intensive management to support sustainable recovery.

While dietitians with dual expertise in diabetes and eating disorders play a crucial role, all healthcare professionals should understand these nutritional principles to provide consistent support.

Awareness, education and staff development

E-learning

A joint adult and paediatric CPD accredited e-learning programme has been developed for Digibete and from 2026 is available to all healthcare professionals involved in the care of patients with diabetes and disordered eating. This has been developed in conjunction with people with lived experience of T1DE. The aim should be to increase awareness, knowledge and skills in the identification and management of this cohort of patients.