Among individuals with severe mental illnesses (SMI) such as schizophrenia and bipolar disorder, rates of comorbid medical conditions are higher than those found in the general population.1 The estimated prevalence of type 2 diabetes (T2D) in this patient group is 10% to 20%, and the onset of T2D occurs approximately 10 to 20 years earlier compared with patients with T2D without SMI.1

The risk for premature death is 3 to 4 times higher among patients with SMI and T2D compared with individuals with neither disease, and worse clinical outcomes have been observed in patients with T2D and SMI compared with those without SMI.1 In a 2011 study, for example, the risk for hospitalization for hypoglycemia or hyperglycemia was 74% higher among patients with T2D with vs without schizophrenia (hazard ratio, 1.74; 95% CI, 1.42-2.12).2

“The association between SMI and [T2D] is multifactorial, including lifestyle factors, possible side effects of antipsychotic medications, genetics, and the biological effects of SMI,” wrote the authors of a systematic review published in 2018 in Primary Care Diabetes.1

Several studies have demonstrated that patients with SMI receive suboptimal treatment for physical conditions such as diabetes.1 Experts have expressed concern that some aspects of the self-management model for T2D may not be practical for patients with SMI, who often face substantial challenges in terms of their living situation and available resources.

Food insecurity is one such issue that influences diabetes management. “If someone is food insecure, they often are unable to purchase foods that are healthy, and this impacts their management of diabetes,” explained Christina Mangurian, MD, MAS, a professor of clinical psychiatry at the University of California, San Francisco, in the School of Medicine. One of the aims of her National Institutes of Health-funded research program is to improve diabetes screening in patients with SMI. “Also, social isolation and lack of safe living environments might influence patients’ capacity to exercise — again, influencing their diabetes care,” she told Endocrinology Advisor.

Despite the clear need for improved management of T2D in patients with SMI, there is scant evidence regarding effective treatment strategies for this group. In a 2018 systematic review of studies regarding interventions to improve diabetes care in this population, only 7 of 1544 publications met inclusion criteria.1 The interventions examined included nutrition and exercise counseling, psychosocial treatment, diabetes education, and behavior modeling.

Collectively, these strategies were associated with minor improvements in several parameters, including glycated hemoglobin (HbA1c) levels (although nonsignificant), weight, fasting plasma glucose level, and diabetes knowledge. Common limitations of these studies included small sample sizes and lack of a similar control group.1

The authors of a 2017 meta-analysis also reported inadequate trial design as well as significant heterogeneity across studies on this topic.3 They examined 48 randomized controlled trials involving measurement of fasting blood glucose or HbA1c in patients with SMI (n = 4052) with or without diabetes, and found that pharmacologic and behavioral approaches reduced fasting glucose but not HbA1c. Subgroup analyses showed that use of metformin and antipsychotic switching strategies led to improvement in HbA1c, and the behavioral approaches with the greatest effect on fasting glucose were those that had a longer duration and included regular physical activity.

“While I definitely believe lifestyle approaches should be encouraged for people with SMI, I think that clinicians should treat these patients with evidence-based pharmacologic treatments such as metformin,” said Dr Mangurian. “Clinicians should also refer patients to locations where they can purchase low-cost healthy food options — and make sure they have the facilities to prepare these foods in their homes.”

Regarding diabetes self-management programs for patients with SMI, a 2016 Cochrane review found insufficient evidence on the topic.4 Only 1 controlled trial was identified, in which participants showed significant improvements in diabetes knowledge and body mass index, but not HbA1c, after participation in the 24-week Diabetes Awareness and Rehabilitation Training program.

As described in a 2018 paper published in the Canadian Journal of Diabetes, Yuliya Knyahnytska, MD, MSc, MSW, PhD, and colleagues at the University of Toronto conducted a critical ethnography to explore the personal experiences of people with co-occurring diabetes and SMI.5 The researchers noted the need for a “shift toward social and contextual understandings of the lived realities of patients,” which may ultimately inform the development of patient-oriented practices and public health strategies.

To explore the topic in depth, Endocrinology Advisor interviewed Dr Knyahnytska as well as Najma Siddiqi, MBChB, MRCP, MRCPsych, PhD, clinical senior lecturer in psychiatry and coauthor of the 2017 meta-analysis mentioned above.3

Endocrinology Advisor: What are some ways in which SMI may affect diabetes outcomes and vice versa?

Dr Siddiqi: SMI has a complex bidirectional relationship with diabetes. There are several mechanisms driving the association — related to the direct consequences of mental illness, its treatment, and also to healthcare inequalities faced by people with mental illness. Socioeconomic factors also play a part; people in lower socioeconomic groups are disproportionately affected by both diabetes and by mental illness.

There is debate about the relative genetic and environmental contributions to the increased diabetes risk. Epidemiologic studies have shown an increased risk even in those who have never taken antipsychotics, and diabetes is more common in family members of people with SMI, suggesting a common inherited susceptibility to both.

SMI affects cognition, motivation, and self-efficacy, which all influence healthy lifestyle behaviors. People with mental illness tend to lead more sedentary lives, have a poorer diet, and have a higher prevalence of smoking. Psychotropics compound these problems because of side effects, which include sedation, tiredness, and weight gain. Even without weight gain, there is evidence that psychotropic medication may impair glucose control.

Despite the higher risk for chronic conditions such as diabetes, the way that healthcare services are organized tends to exclude people with SMI from benefiting from high-quality physical health care. In particular, they are excluded from health promotion and illness prevention messages and from programs that promote self-management of chronic health conditions. This is particularly problematic in diabetes, where more than 90% of the management relies on self-management.

Screening and monitoring of physical health has historically been neglected in these patients, although there has been some progress more recently with several initiatives to improve the physical health of people with SMI in the United Kingdom, including the “No Health Without Mental Health” strategy and a Commissioning for Quality and Innovation framework focusing on physical health in SMI.

Dr Knyahnytska: The combination of T2D and SMI has the potential to overburden existent scarce public health resources and result in diminished and fragmented services for an already underserved population. To address these challenges, a number of healthcare delivery reforms have been developed across Canada during the past decade.

The development and management of diabetes in people with SMI is complex. Managing diabetes and SMI presents a contradictory challenge: while most diabetes care takes place in the everyday life of the diagnosed person away from the routine of the health care system, having SMI requires regular contact with the mental health system. Regular contact with the system is compelled by the chronicity of SMI, assumption of inability to manage self-care and treatment, perceived propensity to violence, and a belief in the need to support clients, which is often experienced as patronizing by service users.

Given these challenges, managing 2 or more complex chronic conditions in everyday life may exacerbate disjunction in health care as numerous — and at times, contradicting — forces will come into play.

Development of T2D has been traditionally associated with potential side effects of antipsychotic medications commonly prescribed to this population and/or the dietary choices made by people with SMI. In line with this understanding, main efforts are directed toward diabetes management, broadly based on a chronic disease management model, which emphasizes patient self-management through compliance with pharmaceutical and lifestyle regimens.

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Endocrinology Advisor: What are examples of the barriers that patients with SMI face in managing their diabetes?

Dr Siddiqi: SMI is characterized by disturbances of thought, perception, affect, and motivation, which influence self-efficacy, literacy, lifestyle behaviors, and family life. These factors make diabetes self-management much more challenging in people with SMI. Most self-management programs for the general population are predicated on significant levels of literacy and self-efficacy. They also do not address the specific difficulties faced by people living with comorbid illness — for example, where the treatment of mental illness with antipsychotic medication may worsen glucose control.

Socioeconomic factors also play a part — SMI is frequently associated with unemployment, housing, and financial difficulties. These factors make it more difficult for people to follow self-management programs which require, for example, the purchase and cooking of healthy food and opportunities to exercise. People with mental illness are often socially isolated and may struggle to participate in groups without additional support.

Dr Knyahnytska: Overall, diabetes management interventions for people with SMI largely mirror those available for the general population, such as focusing on self-management and promoting biomedical parameters of care. [As stated in the paper by Knyahnytska, et al, “Diabetes management continues to operate on the assumption that health behavior change remains an individual responsibility where individuals are presumed to have complete control over their health, including access to appropriate services…. Social science scholars…have called for a public health focus to situate health phenomena as socioeconomic/political creations and, thus, provide a counter to the potential for victim blaming embedded in the self-management model.”5]

Diabetes management of people with SMI in primary care is challenging, both for patients and clinicians. It’s not uncommon to hear much frustration on both sides, with patients expressing their concerns of being dismissed and not listened to, and clinicians struggling to address patients’ noncompliance, which is seen as one of the most important aspects in poor diabetes management.

Both patients and clinicians continue to operate on assumptions of patients’ individual responsibility to “fix” their diabetes through strategies and guidance suggested by clinicians, which are defined by “evidence-based practices.” The struggle is clear: someone with SMI is prone to T2D as a result of numerous factors such as genetics, medications, and poor dietary choices, so the solution is to fix lifestyle (because we can’t really do much about genes and medications), and if this is not happening, then it [must be because patients aren’t doing enough to “fix” it.]

Endocrinology Advisor: What are key recommendations for clinicians who treat these patients? Are there nonpharmacologic aspects of treatment that should be emphasized?

Dr Siddiqi: Research specific to this population to guide clinical practice is sparse. Nevertheless, given the higher risks for diabetes and poorer outcomes, there is an imperative to ensure that diabetes prevention, screening, diagnosis, and treatment interventions are offered to people with SMI as a priority. Most prevention and treatment strategies for the general population will also be relevant for the SMI population. However, people with SMI are a high-risk population and should therefore receive targeted support.

Screening for diabetes should be routine at first presentation, at instigation of antipsychotic medication, and annually thereafter. Prevention of diabetes should be prioritized — including referral to a structured education program focused on healthy lifestyle behaviors such as weight management, physical activity, and smoking. Similarly, people diagnosed with diabetes should be referred to a diabetes self-management program.

However, such programs need to be tailored to account for the additional challenges of living with both diabetes and SMI, as supported by 2018 World Health Organization guidelines.6 There is growing evidence that to be effective, support needs to be intensive and sustained.3 There is some evidence — albeit limited in quantity and quality — that metformin and antipsychotic switching are effective pharmacologic interventions for improving glycemic control.3

Dr Knyahnytska: The dominant perspective in the field of chronic care and diabetes management specifically is managerial or expert based. Diabetes care is largely conceptualized in terms of implications for accountability — personal and systemic — and cost-effectiveness. What this understanding may be missing is that lives and experiences of people with SMI — and any other population, but especially those from low socioeconomic groups — do not occur within neatly structured, expert-defined frameworks. Health professionals are well aware of environmental factors and their impact on clinical practices within everyday setting operations because they are required to work under administrative and fiscal constraints imposed by the dominant order.

There have been numerous studies to demonstrate how patients with SMI experience multiple challenges in daily living, such as stigmatization, problems with access, issues with housing, transportation, and financial difficulties. These difficulties are not unique to this population in any way, and I can safely state that the vast majority of low-income minorities can relate to these challenges as well.

Interestingly, all these multiple environmental constrains, which are well researched and well documented, somehow continue to be seen as “impacting” but not “defining” peoples’ abilities to engage in particular actions. For a patient with SMI living in a boarding home on a very fixed income with food choices defined by the boarding home and food bank, these circumstances of living are not influenced by — implying a possibility of choice — but are organized by their living circumstances.

Experiences of health cannot be detached from the place, time, and living particularities. As clinicians, our goal is to deliver the most appropriate care to achieve the best results and improve quality of life. However, we continue to define means and directions in how to achieve these goals. What often is missing is that our ways and definition may have little, if any, applicability in patients’ lives, as their living actualities are not “risk factors” but the organizations of living which define their actions, and therefore their potential responses to our assignment interventions.

Our lack of attention to the broader socioeconomic actualities of living may therefore [render our interventions] ineffective. For example, healthy food choices may be not feasible for a patient with a fixed income who is living in a boarding home. Or at times, these choices may be painfully dangerous, such as a patient reducing food intake significantly to incorporate more veggies that the person cannot afford, so he chose to eat 1 meal per day and go hungry the rest of the day — this was a real patient I interviewed for my project.

It is tempting to look for a simple solution, choose a simple pill for depression, give another pill for diabetes, and tell patients to decrease carbohydrate intake and go exercise. This is not in any way to dismiss these recommendations, because they are valid and have been demonstrated through research to be very effective. My point is that as human beings, whether with SMI and diabetes or not, we are messy. We live our messy lives in messy environments. We absolutely have the ability to make choices, and I truly believe people have agency to facilitate change.

What I also believe in that often we rely on individual responsibility too much, choosing to ignore our inherited underlying messy complexities. Choosing to focus on individual responsibility steers us away from addressing other issues such as poverty, homelessness, stigma, access, and lack of housing. It is more efficient to see lack of personal responsibility as a problem, as we can pinpoint it, measure it, and advise on it. It is much more challenging to see this within the context of living and work toward social change — and this is exactly where our focus should be as clinicians and global citizens.

Content has been lightly edited for style by Endocrinology Advisor.


1. Grøn AO, Dalsgaard E-M, Ribe AR, et al. Improving diabetes care among patients with severe mental illness: a systematic review of the effect of interventions. Prim Care Diabetes. 2018;12(4):289-304.

2. Becker T, Hux J. Risk of acute complications of diabetes among people with schizophrenia in Ontario, Canada. Diabetes Care. 2011;34(2):398-402.

3. Taylor J, Stubbs B, Hewitt C, et al. The effectiveness of pharmacological and non-pharmacological interventions for improving glycaemic control in adults with severe mental illness: a systematic review and meta-analysis. PLoS One. 2017;12(1):e0168549.

4. McBain H, Mulligan K, Haddad M, Flood C, Jones J, Simpson A. Self management interventions for type 2 diabetes in adult people with severe mental illness. Cochrane Database Syst Rev. 2016;4:CD011361.

5. Knyahnytska Y, Williams C, Dale C, Webster F. Changing the conversation: diabetes management in adults with severe mental illnesses and type 2 diabetes. Can J Diabetes. 2018;42(6):595-602.6.

6. World Health Organization. Management of physical health conditions in adults with severe mental disorders: WHO guidelines. 2018. Accessed January 7, 2019.