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Exploring the challenges of managing diabetes mellitus in an in-patient psychiatric setting

Published online by Cambridge University Press:  04 September 2025

Elegia Clancey
Affiliation:
A core trainee in psychiatry with North East London NHS Foundation Trust, London, UK. She has an interest in comorbid chronic physical health conditions in those with severe mental illness, and the impact of migration and immigration detention on health and well-being.
Parveen Dhesi*
Affiliation:
A general practice specialty trainee with the Royal Free London NHS Hospital Trust, London, UK, and an Academic Clinical Fellow at Queen Mary University of London, UK. She has an interest in public health challenges faced at local community levels and in using qualitative methods to explore the effect of societal marginalisation on health and healthcare.
Prachi Patel
Affiliation:
A Foundation Year 2 doctor currently working in cardiology at Whipps Cross Hospital (Barts Health NHS Trust), London, UK. She has an interest in anaesthetics and emergency medicine.
Ioanna Zimianiti
Affiliation:
A clinical fellowship in neurology at Geneva University Hospitals (Hôpitaux Universitaires de Genève), Geneva, Switzerland. She completed her Foundation training at Bart’s Health NHS Trust, with which she is affiliated.
Milly Biswas
Affiliation:
A consultant psychiatrist with East London NHS Foundation Trust, London, UK. She is passionate about advancing psychiatric research to advance healthcare services.
*
Correspondence Parveen Dhesi. Email: parveen.dhesi@nhs.net
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Summary

Diabetes mellitus affects about 830 million people worldwide, with 2.5 million diabetes-related deaths per year. The estimated prevalence of diabetes among psychiatric in-patients in the UK is 10%, and the increased risk of poor diabetes-related physical health outcomes among people with a severe mental illness (SMI) is detrimental to their mental health and social functioning. This article uses two fictitious case vignettes inspired by experience in an in-patient psychiatric facility to explore the challenges of managing diabetes in this setting in the UK. The relationship between psychiatric disorders, their symptoms and management of physical health conditions, including health promotion, monitoring and pharmacological therapy, creates a challenge in the optimal management of diabetes. Recommendations for improving diabetes management in people with SMI are divided into those requiring insulin and those not requiring insulin.

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This is an Open Access article, distributed under the terms of the Creative Commons Attribution-NonCommercial-ShareAlike licence (https://creativecommons.org/licenses/by-nc-sa/4.0/), which permits non-commercial re-use, distribution, and reproduction in any medium, provided the same Creative Commons licence is used to distribute the re-used or adapted article and the original article is properly cited. The written permission of Cambridge University Press must be obtained prior to any commercial use.
Copyright
© The Author(s), 2025. Published by Cambridge University Press on behalf of Royal College of Psychiatrists

LEARNING OBJECTIVES

After reading this article you will be able to:

  • discuss the relationship between diabetes and severe mental illness

  • understand the challenges of managing diabetes in an in-patient psychiatric setting

  • consider potential strategies for ensuring optimal management of people with diabetes and severe mental illness.

Diabetes mellitus is a chronic metabolic disease categorised by ineffective insulin production and/or utilisation. There are approximately 830 million people living with diabetes globally and 2.5 million diabetes-related deaths per year (World Health Organization 2024). This high burden of disease positions diabetes as a public health priority.

Inadequately controlled diabetes is associated with significant complications contributing to increased morbidity and mortality (Harding Reference Harding, Pavkov and Magliano2019). Poor glycaemic control is associated with an increased risk of such complications, including cardiovascular disease, retinopathy, nephropathy, neuropathy and peripheral vascular disease. Although there are many types of diabetes mellitus, this article discusses type 1 (T1DM) and type 2 diabetes (T2DM); for conciseness, we will refer to diabetes, rather than diabetes mellitus.

Diabetes is diagnosed when an individual has symptoms or signs consistent with the disorder (Box 1) alongside persistent hyperglycaemia. Persistent hyperglycaemia is defined by the National Institute for Health and Care Excellence (NICE) as a glycated haemoglobin (HbA1c) level >48 mmol/mol (6.5%), fasting plasma glucose level >7 mmol/L or random plasma glucose level >11.1 mmol/L. In the absence of symptoms or signs, a repeat test would be needed to diagnose diabetes (NICE 2025).

BOX 1 Signs and symptoms of diabetes

Type 1 diabetes

  • Ketosis

  • Rapid weight loss

  • Age at onset <50 years (although should not be discounted if the person is aged >50 years)

  • BMI <25 kg/m2 (although should not be discounted if the person presents with a BMI >25)

Type 2 diabetes

  • Persistent hyperglycaemia

  • HbA1c >48 mmol/mol OR fasting plasma glucose level >7 mmol/L OR random plasma glucose level >11.1 mmol/L

Possibly accompanied by any of the following:

  • Symptoms: polydipsia, polyuria, blurred vision, unexplained weight loss, recurrent infections, tiredness

  • Signs: acanthosis nigricans (a skin condition causing dark pigmentation of skin folds, typically the axillae, groin and neck), suggesting insulin resistance

(Adapted from: NICE 2024a, 2025)

Exploring the relationship between diabetes and severe mental illness

Severe mental illness (SMI) is a term used to describe major psychiatric disorders such as schizophrenia, psychotic depression and bipolar disorder (Holt Reference Holt and Mitchell2015). The life expectancy of people with SMI is reduced by at least 15 years compared with the general population. A substantial proportion of this reduced life expectancy is attributed to increased cardiovascular disease, for which T2DM is a significant risk factor. The prevalence of diabetes in people with SMI is estimated to be two to three times higher than in the general population (Das-Munshi Reference Das-Munshi, Ashworth and Dewey2017) – overall, it is estimated to be present in 10–15% of those with schizophrenia and in 8–17% of those with bipolar disorder (De Hert Reference De Hert, Dekker and Wood2009). The prevalence of diabetes in those admitted to a psychiatric unit in the UK is also higher than in the general population, with one systematic review estimating the prevalence of all types of diabetes to be 10% in this setting (Roberts Reference Roberts, Jones and Blackman2017).

The relationship between depressive disorders and diabetes is understood to be bidirectional. People with diabetes are more likely to have depression, with evidence to suggest that diabetes doubles the odds of comorbid depression (Anderson Reference Anderson, Freedland and Clouse2001), and those with depression are more likely to develop diabetes (Pan Reference Pan, Lucas and Sun2010). Depression is also associated with poor glycaemic control in those with diabetes (Lustman Reference Lustman, Anderson and Freedland2000), which may be due to poor medication concordance, poor diet, barriers to accessing care and other lifestyle factors (Akhaury Reference Akhaury and Chaware2022). Much of the management of diabetes depends on self-care, which is often impaired in those with depressive disorders.

The relationship between schizophrenia and diabetes is multifactorial and complex, with multiple contributing genetic, biological and psychosocial factors. Studies have shown that 50% of those with schizophrenia have a family history of diabetes and that unaffected relatives have impaired glucose tolerance (Misiak Reference Misiak, Wiśniewski and Lis2020). Research indicates that antipsychotic-naive individuals presenting with their first episode of psychosis have signs of subclinical metabolic dysregulation, in terms of both glucose homeostasis and lipid profile disturbances. There is also evidence of impaired hormonal regulation of appetite, with increased insulin levels and low leptin levels in people with early psychosis before antipsychotic initiation (Misiak Reference Misiak, Bartoli and Stramecki2019). Furthermore, it has been suggested that there are common mechanisms in both T2DM and schizophrenia, such as inflammation, oxidative stress and hypothalamic–pituitary–adrenal (HPA) axis dysfunction (Mizuki Reference Mizuki, Sakamoto and Okahisa2020).

Case vignettes

Read the case vignettes below and reflect on the interaction between diabetes and SMI for these individuals. The vignettes are fictitious, based on an amalgamation of experiences and challenges faced when managing diabetes in an in-patient psychiatric setting.

Vignette 1: Managing T1DM in an in-patient psychiatric setting

John, a 32-year-old White man with a background of schizophrenia and T1DM presented to the emergency department in diabetic ketoacidosis (DKA). He had been found wandering the streets and was reported to be behaving bizarrely by a passer-by. Once DKA had been appropriately managed, John was admitted to a psychiatric unit under section 2 of the Mental Health Act 1983. This was because a relapse of psychosis was causing him to experience delusional beliefs, paranoia and hallucinations.

John was prescribed his usual insulin regimen. However, during the first few weeks on the ward his blood glucose levels were difficult to manage. He had multiple episodes of hyperglycaemia and required rapid-acting insulin doses several times a day. His background of persecutory delusional beliefs and reluctance to be in hospital made John extremely suspicious of staff members monitoring his blood glucose, leading him to frequently refuse monitoring. He also exhibited erratic eating patterns, making insulin dosing difficult to predict. He was generally suspicious about medications given to him and therefore was only partially adherent to his usual insulin regimen.

A diabetic specialist nurse became involved in John’s care and was able to provide the ward staff with consistent expert advice. A continuous blood glucose monitoring (CBGM) device was used to reduce the need for finger-prick monitoring, and a basal–bolus insulin regimen was introduced to tackle John’s erratic eating habits.

Reflection

What do you think were the main challenges the ward staff encountered when managing John’s diabetic control?

Vignette 2: Managing the interaction between physical and mental health in an individual with SMI

Clara, a 45-year-old South Asian woman with a background of schizophrenia, diagnosed at age 22, was admitted to a psychiatric unit with features of a severe relapse with psychotic symptoms.

Her symptoms had been well controlled by olanzapine for the past 20 years; however, at her last annual review she was found to be prediabetic (HbA1c of 46 mmol/mol) with an increasing body mass index (BMI increased from 24 to 29 kg/m2 over the past 5 years). She had been enrolled in the Healthier You NHS Diabetes Prevention Programme by her general practitioner (GP). Initially, Clara made good progress on the programme and found the group support element particularly motivating. However, she struggled to remain engaged owing to her busy work schedule and consequently lost motivation and consistency. After 5 months Clara did not see the progress she had hoped for. She had read online that olanzapine might be contributing to her metabolic state – this led to her skipping olanzapine doses. Unfortunately, her psychotic symptoms returned, resulting in an admission to an in-patient psychiatric ward.

On admission, Clara’s metabolic status had deteriorated; her HbA1c was now 58 mmol/mol (subsequently a diagnosis of T2DM was made) and this was accompanied by raised lipids, a BMI of 30 kg/m2 and waist circumference of 39 inches (99 cm). After being recommenced on olanzapine her blood glucose levels remained elevated. Since her diagnosis of T2DM Clara’s adherence to olanzapine became poor, threatening the effective treatment of her psychotic symptoms. Eventually, the decision was made to switch her antipsychotic treatment to aripiprazole, in the hope of reducing the metabolic effects while not compromising the treatment of her psychosis.

Reflection

How might T2DM affect the management of people with chronic schizophrenia?

What factors might affect people with SMI engaging in health promotion strategies and how could these be addressed?

Reflections from the case vignettes

Diabetes management and risk awareness

These case vignettes demonstrate the many challenges clinicians face when managing diabetes and SMI concurrently. John’s relapse of psychotic symptoms, such as paranoia and delusional beliefs leading to erratic eating habits and suspicion of his medications, affected his ability to manage his T1DM and insulin regimen appropriately. He required several doses a day of rapid-acting insulin to correct unpredictable blood glucose values, with wide fluctuations in plasma glucose requiring multiple, frequent reviews by doctors and the specialist diabetic nurse. Furthermore, DKA is a serious complication in people with diabetes requiring insulin therapy; in a person with SMI the risk of delayed presentation and/or diagnostic overshadowing due to the presumption of psychiatric symptoms could have a detrimental impact on mortality and morbidity. Therefore, it is crucial that medical and mental health professionals have appropriate awareness of the possible risks and complications of diabetes, which includes recognising the signs and symptoms of DKA (Box 2). In this example, the use of CBGM was a beneficial management strategy that allowed professionals to monitor John’s blood sugar less invasively, providing both reassurance and easier titration of insulin. For John, CBGM was appropriate. However, for some people a device attached to their body may be unacceptable and could trigger persecutory beliefs. In such situations, it is important to work with the individual and the multidisciplinary team to create appropriate management plans.

BOX 2 Recognising features of diabetic ketoacidosis (DKA)

Features

  • Abdominal pain

  • Nausea and/or vomiting

  • Polyuria

  • Polydipsia

  • Dehydration

  • Kussmaul respiration (deep hyperventilation)

  • Acetone-smelling breath

Diagnostic criteria

  • Glucose level >11 mmol/l

  • Urine ketones 2+ on dipstick

  • Blood pH <7.3 or bicarbonate <15 mmol/l (although these cannot be usually measured on the in-patient ward)

If features of DKA present, measure glucose and ketones and if these are suggestive of DKA, ensure that the patient is urgently transferred to a hospital.

(Adapted from: NICE 2024b)

Appropriate use of mental health legislation

It is important to consider legal frameworks when treating patients with comorbid SMI and diabetes. In England and Wales, there is a role for both the Mental Capacity Act 2005 and the Mental Health Act 1983 when treating individuals who present with acute physical and mental illness. Both Acts provide a legal framework by which people can be deprived of their liberty; however, the clinical decision-making processes involved differ (Gilburt Reference Gilburt2021). In John’s case, initial treatment for DKA was provided under the Mental Capacity Act, as he lacked the capacity to make informed decisions about treatment for this life-threatening emergency. Following appropriate treatment of DKA and stabilisation of his blood glucose levels, John continued to experience paranoia, delusional beliefs and hallucinations. He was then assessed using the Mental Health Act and was detained under section 2 for assessment and treatment in a psychiatric unit. While on the ward, his capacity was reassessed specifically regarding managing his diabetes and consenting to insulin. In the event of another diabetic emergency, his capacity to accept or decline treatment would be assessed again.

Distinguishing mental incapacity from a mental disorder can pose significant challenges for clinicians, and inadequate assessment and inappropriate use of legal powers can lead to unnecessary detention. Mental health clinicians often have an enhanced understanding and appreciation of these legal processes and should be involved in decision-making for people with SMI where possible.

Patient-centred management of concurrent SMI and diabetes

Clara’s case demonstrates how the fear of developing diabetes due to olanzapine led to her stopping medication, despite taking it successfully for many years. This example demonstrates the complex interplay between physical and mental health and antipsychotic regimens, which contributed to Clara’s disengagement and eventual admission to hospital. It highlights the importance of using the right psychotropic agent for the individual, considering their metabolic risk and tailoring ways to help individuals manage their illnesses. This is particularly important in diabetes treatment, given the rising use of sodium–glucose cotransporter 2 (SGLT2) inhibitors and glucagon-like peptide-1 (GLP-1) receptor agonists, anti-diabetic drugs that have been shown to significantly reduce metabolic risk.

In this case, olanzapine was changed to aripiprazole, which has a lower risk of metabolic syndrome. However, as with any change in antipsychotics, there are uncertainties regarding how effective this will be. If Clara’s psychotic symptoms remained prominent, what would the next step be? Cases such as these require a sensitive approach; Clara’s physical health is clearly important to her, and so ongoing opportunities should be offered to discuss her concerns. It would also be helpful for her to receive additional support for her new diagnosis of diabetes, particularly after her psychosis subsides, and that she has out-patient follow-up arranged with the diabetic team. Generally, discharge from an in-patient psychiatric unit could also be an opportunity to facilitate re-engagement with community diabetes (and other healthcare) teams, particularly as people with SMI are more vulnerable to physical health complications (see Table 1 for the common complications of diabetes and screening recommendations).

TABLE 1 Physical health complications of diabetes and screening recommendations

Adapted from: NICE (2024a, 2025).

Challenges of managing diabetes and SMI

Managing diabetes in an in-patient psychiatric setting

The management of diabetes depends on the type, broadly involving lifestyle measures, education and medications. Diabetes can be treated using various anti-diabetic medications, with insulin being used in both T1DM and T2DM that is difficult to manage. There are well-established education courses provided for people with any type of diabetes; however, patients are generally supported by services offered by their GP and the specialist diabetic teams. Examples of services in the UK include the above-mentioned Healthier You NHS Diabetes Prevention Programme, the NHS Type 2 Diabetes Path to Remission Programme and the NHS Diabetes Weight Management Service. These services offer patient education, HbA1c monitoring, medication reviews and physical health checks such as blood pressure monitoring, renal function monitoring, retinal screening and diabetic foot checks, allowing early detection and management of physical health complications (NICE 2025). Good management and control of diabetes and prevention of sustained hyperglycaemia are key in the prevention of diabetic complications/morbidity and mortality. There is currently a lack of access and standardisation of diabetes management across NHS in-patient psychiatric services for individuals with SMI (Goff Reference Goff, Sharma and Varvari2024). Various barriers hinder the provision of adequate care, complicating the overall management process.

A significant barrier involves the lack of communication and handover between physical health services and mental health services at the time of admission to a psychiatric ward. This lack of coordinated care between physical and mental healthcare providers can result in critical gaps in patient management, ranging from inappropriate blood glucose monitoring (Kelbrick Reference Kelbrick and Picchioni2013) to incorrect prescribing of critical drugs such as insulin (Goff Reference Goff, Sharma and Varvari2024). Incomplete handovers carry the risk of causing patient harm, particularly in the case of incorrectly prescribed medications, with patients diagnosed with an SMI such as schizophrenia having a significantly higher rate of hospital admission for hypo- or hyperglycaemia (Chen Reference Chen, Yang and Hsu2020).

Confidence within mental health teams can also significantly vary when managing in-patients with diabetes. Qualitative studies in health trusts within the UK have demonstrated that mental health professionals felt less confident in the management of diabetes and believed that they would benefit from more education on this topic (McBain Reference McBain, Lamontagne-Godwin and Haddad2018). Crucially, this could result in fewer in-patients being managed according to current diabetes care standards. For example, lack of confidence about diabetes parameters could lead to late diagnosis, and lack of knowledge of monitoring requirements increases the risk of multi-organ complications. This further exacerbates the discrepancies in delivering high-quality care.

People with SMI may themselves struggle to work with mental health professionals when managing their diabetes, owing to limitations in cognitive and executive functioning (McBain Reference McBain, Lamontagne-Godwin and Haddad2018), particularly when in an acute phase of illness warranting in-patient admission. This can often lead to poor communication between patients and mental health staff, leading to difficulties in motivating and empowering patients to manage their diabetes safely while in hospital (McBain Reference McBain, Lamontagne-Godwin and Haddad2018).

Medication in the management of concurrent diabetes and SMI

An important challenge to consider when discussing diabetes management in psychiatric settings is antipsychotics and metabolic syndrome. Second-generation antipsychotics are a well-known risk factor in the development of T2DM, primarily through weight gain and adverse effects on insulin sensitivity and secretion, with the pathophysiology being related to the antagonism of histamine H1 and serotonin 5-HT2c receptors (Medved Reference Medved, Jovanović and Knapić2009). Indeed, it is thought that most of the metabolic risk associated with psychotic disorders such as schizophrenia is due to antipsychotic medication (Annamalai Reference Annamalai and Tek2015).

There is a hierarchy of risk associated with antipsychotic treatment. Clozapine and olanzapine have the greatest weight gain potential; this is particularly rapid with clozapine, with 55% of patients gaining weight within the first 3 months of treatment – the disruption of glucagon-like peptide-1 (GLP-1) is thought to play a role here (Tso Reference Tso, Kumar and Jayasooriya2017). Quetiapine and risperidone have an intermediate risk, whereas aripiprazole has little effect on weight and glycaemic control (De Hert Reference De Hert, Correll and Bobes2011). Given the risk of diabetes-related complications and consequent increase in mortality, most guidance recommends switching to lower-risk antipsychotics should lifestyle measures be deemed ineffective (Cooper Reference Cooper, Reynolds and Barnes2016). However, the efficacy and tolerability of antipsychotic agents greatly varies between individuals, and this approach carries the risk of ineffective control of psychotic symptoms (Cooper Reference Cooper, Reynolds and Barnes2016). Alternatively, should patients be kept on their original antipsychotic regime there is a risk of non-adherence to antipsychotic medication, given their significant side-effect profile – particularly weight gain (Velligan Reference Velligan, Weiden and Sajatovic2009) – again increasing the risk of relapse. This clinical picture is further complicated by the issue of polypharmacy. Anti-diabetic agents are often indicated to manage metabolic side-effects and increase insulin sensitivity (Cooper Reference Cooper, Reynolds and Barnes2016) but bring possible risks, such as hypoglycaemia, ‘sick day rules’ (the pausing of certain medications during dehydrating illness) and increasing pill burden, which affects medication adherence (De Hert Reference De Hert, Correll and Bobes2011).

Recommendations for the management of diabetes in individuals with SMI

Preventing and managing diabetes

Screening and monitoring of metabolic parameters

Presentation to an in-patient psychiatric setting provides a good opportunity to assess a person’s metabolic status and risk of T2DM. For diabetes screening, an oral glucose tolerance test is the most sensitive test, but this is not commonly used in the UK outside of pregnancy. Therefore, HbA1c or random glucose monitoring may be more appropriate (Taylor Reference Taylor, Stubbs and Hewitt2017). Symptoms of hyperglycaemia such as polydipsia, polyuria, weight loss or unexplained infections and increased appetite should also be assessed (NICE 2025).

Besides glucose control, other metabolic parameters should be measured, especially in patients taking antipsychotics. A summary of the recommended monitoring tests and their frequency is given in Supplementary File 1, available online at https://doi.org/10.1192/bja.2025.10134. For trusts using electronic health records, specific order sets as well as electronic reminders could be used to increase adherence to monitoring standards.

To improve adherence to these monitoring recommendations, in-patient psychiatric units should be encouraged to take part in the National Diabetes Inpatient Safety Audit (NDISA) to identify the level of provision for people with diabetes and identify areas for improvement (Joint British Diabetes Societies for Inpatient Care 2017). This may help improve the screening and monitoring of metabolic parameters in patients with diabetes and help to avoid safety incidents relating to diabetes, such as severe hypoglycaemia or diabetic emergencies.

Following discharge, there should be a clear handover from the in-patient to the community team, to ensure continuity of care. Template letters highlighting the physical health risks associated with SMI and with antipsychotic medication may be helpful (Tso Reference Tso, Kumar and Jayasooriya2017). Additionally, the use of individualised ‘diabetes passports’, which would include a patients’ blood results, treatments and required monitoring alongside their personal routines, could be used to improve communication between teams and aid in empowering individuals to have some control of their care (Simmons Reference Simmons, Gamble and Foote2004). Primary care teams should plan for appropriate management. However, as mentioned above, people with SMI may have difficulty engaging with mental and physical healthcare teams concurrently (McBain Reference McBain, Lamontagne-Godwin and Haddad2018). For individuals with diabetes that is particularly difficult to manage, specialists could be invited to discharge planning meetings to ensure an appropriate plan for follow-up is made. Further, the patient’s diabetes passport would allow easy identification of diabetic care needs, so that any professional involved with managing the health and well-being of that individual can facilitate care. For example, community care-coordinators could facilitate booking and reminding of appointments for monitoring if the requirements are clearly set out. For patients detained under section 3 of the Mental Health Act, the section 117 aftercare provision could also be utilised to cover diabetes healthcare provision in the community.

Lifestyle interventions

As in the general population, lifestyle interventions, such as the combination of psychoeducational programmes with dietary guidance and physical training, are recommended first-line, and there is evidence that they can be effective in SMI (Cooper Reference Cooper, Reynolds and Barnes2016). In a meta-analysis, Taylor et al (Reference Taylor, Stubbs and Hewitt2017) found that lifestyle measures improved fasting blood glucose but with no effect on HbA1c levels in adults with SMI. The latter might be due to the relatively short duration of interventions delivered across the included studies. Subgroup analysis demonstrated that better outcomes were seen when interventions included a physical activity component and lasted for more than 6 months. Caemmerer et al (Reference Caemmerer, Correll and Maayan2012) pooled evidence from 17 studies in in-patient, out-patient and mixed settings and demonstrated that interventions based on cognitive–behavioural therapy and nutritional and/or exercise components can lead to weight loss and significantly improve other metabolic parameters, such as waist circumference, percentage body fat and lipid profile. These studies included patients with and without a diagnosis of T2DM, indicating that behavioural interventions can be effective in both prevention and management. However, sensitivity analysis indicated that positive results in weight change and BMI were significant only for out-patient interventions, potentially owing to the small numbers of in-patient trials.

Symptoms of SMI, such as negative symptoms of schizophrenia, often hinder patients’ motivation and engagement, posing barriers to the implementation of lifestyle interventions. To address this, Ball et al (Reference Ball, Yung and Bucci2022) suggest that staff should receive training to understand how SMI symptoms affect patient engagement, gain deeper insights into patients’ routines and symptoms, and serve as positive role models. In keeping with this idea, Somerset Partnership NHS Foundation Trust have appointed ‘healthy lifestyle officers’, whose role is to encourage in-patients to become more physically active by offering activities including using gym facilities, group sports, local walks and cycling (Nursing, Midwifery and Allied Health Professions Policy Unit 2016). Additionally, incorporating exercise and dietary interventions into personalised care plans can foster a healthier culture on the ward. This is especially important for long-stay patients, such as those admitted to forensic units, where time away from the ward is more limited. Finally, staffing levels should be optimised, as inadequate cover and supervision often limits patient engagement in health promotion activities such as accessing gym facilities.

Antipsychotic choice

The propensity of certain antipsychotics to increase the risk of diabetes should be considered when initiating and altering antipsychotic medication. However, there is an appreciation that this must be balanced with the use of effective antipsychotics to control symptoms of SMI. Antipsychotic switch has also been recommended to mitigate adverse effects (Taylor Reference Taylor, Stubbs and Hewitt2017). A meta-analysis (Pillinger Reference Pillinger, McCutcheon and Veno2020) investigated the dynamic relationship between antipsychotics, symptom management and metabolic parameters. It found marked differences between antipsychotics, with olanzapine and clozapine having the worst metabolic effect. Antipsychotics such as aripiprazole and risperidone had the most benign metabolic effect. These findings are in keeping with previous studies investigating similar outcomes. In addition, factors including increased weight, male gender and ‘non-White’ (not defined) ethnicity were predictors of increased susceptibility to antipsychotic-induced metabolic changes. Most studies required patients to be stable from a psychiatric standpoint and therefore the findings may not be applicable to acute admissions in the in-patient ward.

The role of anti-diabetic medication

Metformin is recommended for first-line pharmacological treatment of T2DM (Cooper Reference Cooper, Reynolds and Barnes2016). A Cochrane meta-analysis demonstrated that metformin may also prevent weight gain in people with schizophrenia, although interpretation of these results is limited by the small number of studies identified, their small sample size and the limited duration of follow-up (Agarwal Reference Agarwal, Stogios and Ahsan2022). When additional medications are required, the need for tight glucose control should be balanced against the risk of hypoglycaemia (Annamalai Reference Annamalai and Tek2015). Oral agents with reduced risk of weight gain might have a particular role in people with SMI, in contrast to agents such as sulfonylureas (Holt Reference Holt and Mitchell2015). These include dipeptidyl peptidase 4 and SGLT2 inhibitors (Holt Reference Holt and Mitchell2015). Agents with a propensity to cause hypoglycaemia, such as sulfonylureas and insulin, should be used with caution in people with SMI (Lally Reference Lally, O’ Loughlin and Stubbs2018). Other drugs that are being increasingly used include GLP-1 analogues such as liraglutide or semaglutide, which aside from improving glucose control can also lead to improvements in weight, BMI and lipid profile (Larsen Reference Larsen, Vedtofte and Jakobsen2017). In the UK, these drugs are prescribed within specialist services and therefore clinicians should refer patients who might benefit, such as those with a BMI above 30 kg/m2 who cannot be managed in tier 2 services, to a metabolic clinic (NICE 2023). See Supplementary File 2 for an overview of the management options for T2DM.

Managing diabetes requiring insulin therapy

Insulin is necessary in people with T1DM and is often needed in T2DM. Therefore staff should be trained to support insulin administration and recognise symptoms and signs of DKA and hypoglycaemia (Boxes 2 and 3). Staff should be aware of local guidelines regarding the management of diabetic emergencies.

BOX 3 Signs and symptoms of hypoglycaemia

Mild hypoglycaemia

  • Hunger

  • Anxiety or irritability

  • Sweating

  • Tingling lips

  • Palpitations

  • Tremor

Moderate hypoglycaemia

  • Weakness and lethargy

  • Impaired vision

  • Incoordination

  • Reduced orientation

  • Confusion

  • Irrational behaviour

  • Emotional lability

  • Deterioration of cognitive function (blood glucose level <3.0 mmol/L)

Severe hypoglycaemia

  • Convulsions

  • Inability to swallow

  • Loss of consciousness

  • Coma

(Adapted from: NICE 2024c)

We recommend that all in-patient wards have pathways in place to access urgent and non-urgent advice on diabetes management, for example via a nurse specialist who can follow up in-patients and provide staff training and support on the safe use of insulin (Goff Reference Goff, Sharma and Varvari2024). Finally, in the context of the in-patient ward, regular glucose monitoring might be challenging to achieve yet is necessary – especially in the context of T1DM. CBGM systems could be especially useful in this context.

Conclusions

Diabetes and SMI individually pose serious health implications for individuals. There is an increased prevalence of diabetes in in-patient psychiatric settings owing to a multitude of biopsychosocial and medication-related interactions. The notable higher prevalence of diabetes in individuals with SMI indicates that better healthcare interventions are required.

Services for diabetes treatment are largely offered by GP and diabetic specialist teams, and they encompass a wide range of care (NICE 2025). However, these services are rarely – or inconsistently – available to individuals in in-patient psychiatric settings (Goff Reference Goff, Sharma and Varvari2024). Improving access to primary and secondary prevention strategies in the community for people experiencing SMI will promote early identification and management of complications of diabetes. Better education for psychiatric teams should be prioritised. This may help to empower teams to take responsibility in facilitating/monitoring people’s access to diabetes services, including regular eye screening, adjustment of anti-diabetic medication, multi-organ disease monitoring and diabetic foot reviews.

Targeted health promotion strategies for people with SMI can ensure that services adequately cater for specific barriers and needs of this population. More research is needed to help understand the challenges experienced by those with SMI in relation to diabetes. Quality improvement studies and future research should target specific areas, for example acute relapse of psychosis and diabetes, the use of long-term lifestyle interventions in long-stay in-patients, psychiatric in-patient management of diabetes and targeted health promotion strategies for those with SMI.

Overall, the management of diabetes in in-patient psychiatry remains suboptimal, with factors such as poor coordination between services, lack of staff confidence and patients’ characteristics affecting the delivery of care. These areas need to be addressed to optimise diabetes care and address the significant health disparities between those with SMI and those without.

MCQs

Select the single best option for each question stem

  1. 1 At what HbA1c level would a diagnosis of diabetes be made?

    1. a 38 mmol/mol

    2. b 42 mmol/mol

    3. c 48 mmol/mol

    4. d 54 mmol/mol

    5. e 58 mmol/mol.

  2. 2 A 46-year-old female is admitted to the in-patient psychiatric ward with mania and suspected bipolar affective disorder. She has a history of high cholesterol, hypertension, migraines, T1DM and eczema. Of her regular medication, which is the most pertinent to be prescribed immediately on admission?

    1. a topical steroid creams

    2. b atorvastatin

    3. c ramipril

    4. d insulin regimen

    5. e naproxen for acute migraine attacks.

  3. 3 Which of the following antipsychotic medications is associated with the greatest risk of metabolic syndrome?

    1. a aripiprazole

    2. b quetiapine

    3. c amisulpride

    4. d asenapine

    5. e clozapine.

  4. 4 What is the estimated prevalence of diabetes (all types) among psychiatric in-patients in the UK?

    1. a 2%

    2. b 10%

    3. c 20%

    4. d 22%

    5. e 46%.

  5. 5 You are the on-call doctor for the psychiatry in-patient facility. You are called to assess Kyle, a 34-year-old male with a background of bipolar disorder, asthma and T1DM. He had presented to the in-patient psychiatric unit following an episode of mania, including erratic eating patterns and denial of physical health conditions. The nursing staff inform you that Kyle had been complaining of abdominal pain before becoming disoriented and drowsy. What acute complication needs to be considered as a cause of Kyle’s symptoms?

    1. a hypoglycaemia

    2. b mania

    3. c opiate overdose

    4. d diabetic ketoacidosis

    5. e bowel obstruction.

MCQ answers

  1. 1 c

  2. 2 d

  3. 3 a

  4. 4 b

  5. 5 d

Supplementary material

The supplementary material is available online at https://doi.org/10.1192/bja.2025.10134.

Data availability

Data availability is not applicable to this article as no new data were created or analysed in this study.

Acknowledgements

We thank Dr Akash Doshi, Endocrinology Registrar (ST7), for their contribution and comments.

Author contributions

All authors contributed to the idea development and revision of the manuscript. E.C., P.D., P.P. and I.Z. contributed equally to the production of the manuscript.

Funding

This research received no specific grant from any funding agency, commercial or not-for-profit sectors.

Declaration of interest

None.

Footnotes

*

Joint first authors.

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Figure 0

TABLE 1 Physical health complications of diabetes and screening recommendations

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