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.

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).

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, HbA_1c 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 HbA_1c 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.