Title: Improving diabetes outcomes for people with severe mental illness (SMI): a longitudinal observational and qualitative study of patients in England
Funder: Department of Health and Social Care

Abstract: Background: People with SMI have poorer physical health and lower life expectancy than the general population. A two to three-fold increased risk of diabetes and its associated complications contributes to this health inequality. Little is known about the relative influence of risk factors on the onset of diabetes and its outcomes in SMI; or about the diabetes care that people with SMI receive, and how this may contribute to the established health inequalities in this population. Aim: The overarching goal of our research programme is to improve diabetes outcomes for people with SMI. The present proposal contributes to that goal and aims to identify the determinants of diabetes and explore variation in diabetes outcomes for people with SMI in order to develop potential healthcare interventions that can be tested further. Our key research questions in this study are: 1) What are the socio-demographic and illness-related risk factors associated with a) developing diabetes in people with SMI? b) variation in diabetes and mental health outcomes in people with SMI and diabetes? 2) How do physical and mental health outcomes differ between people with SMI and diabetes, a) compared to people with SMI without diabetes? b) compared to people with diabetes but no SMI? 3) What factors influence access to, and receipt of, diabetes care for people with SMI, and how are diabetes healthcare interventions experienced by people with SMI? 4) How and at what cost is diabetes monitored and managed in people with SMI compared to those without SMI? 5) What healthcare interventions (e.g. medication, referrals and care pathways) are associated with better diabetes outcomes for people with SMI and diabetes? Methods: We will use a concurrent triangulation mixed methods design combining quantitative analyses of anonymised patient records, and a qualitative study of patients with co-existing SMI and diabetes, their carers, and healthcare staff. The quantitative study will interrogate linked primary care and hospital records for a large representative sample of i) adults with SMI, ii) adults with SMI and diabetes and iii) a matched control group of adults with diabetes but no SMI. Using these datasets, we will measure associations between various factors and development of diabetes in people with SMI; and variation in health outcomes in people with comorbid SMI and diabetes. We will explore variations in diabetes screening, monitoring and management, and estimate costs for these; and investigate how healthcare interventions may contribute to health outcomes. The qualitative study will also explore these themes, using thematic analysis of semi-structured interviews to understand how diabetes is managed alongside SMI. Findings from each study will be integrated to develop a fuller understanding of the relationship between SMI and diabetes, and used in two co-design workshops to design targeted interventions and agree recommendations for practice. Potential Impact: This study will address important gaps in evidence about which people with SMI experience poor diabetes outcomes and why; and how healthcare services might be changed to better support these patients. Better prevention and management of diabetes has the potential to significantly reduce the risk of diabetes complications, deliver large cost savings for the NHS, and help reduce health inequalities (including life expectancy and morbidity), experienced by people with SMI.

Lay abstract: Background: Severe mental illness ‘SMI’ describes a group of illnesses (such as schizophrenia and bipolar disorder) in which ‘psychosis’ occurs. Psychosis describes the loss of reality a person experiences so that they stop seeing and responding appropriately to the world they live in. People with SMI have poorer physical health and a shorter life expectancy compared to the general population. We know diabetes is partly to blame; people with SMI are 2-3 times more likely to develop diabetes, and get more complications because of their diabetes (such as blindness, kidney problems, strokes, and death). We know of several reasons for this, including the individual’s mental illness, its treatment, unhealthy behaviours (e.g. lack of exercise, smoking) and poverty. However, we do not know how much each of these factors contributes to the increased risk of diabetes and its complications. There is also limited understanding about how diabetes is managed for people with SMI and at what cost, and how this might affect their physical and mental health. Finally, we do not know what might prevent people with SMI from accessing appropriate diabetes care and how best to support them to manage their diabetes. This study will help to address these gaps in knowledge, so that we can learn how to improve diabetes care for people with SMI and target those at greatest risk. Aim: We aim to find out why patients with SMI are more likely to develop diabetes and have more complications from their diabetes; and to understand how the provision of diabetes care might contribute to this, in order to design improvements. Design: We will use anonymised routinely collected information from health records to find out which patients with SMI are at greatest risk of developing diabetes and experiencing diabetes complications, and why; and how SMI and diabetes impacts on mental and physical health. We will examine how diabetes is screened for, monitored and managed to understand what helps to improve diabetes outcomes and how much this costs. At the same time, we will explore these themes in interviews with people with SMI who also have diabetes, their carers, and healthcare staff. We will also explore the experience of diabetes care and identify barriers to accessing care. We will merge the findings from healthcare records and interviews to allow for a more in-depth exploration of the relationship between SMI and diabetes. We will use these findings in co-design workshops with patients, carers and healthcare staff to consider how diabetes care for people with SMI needs to be modified, and to design and test out ideas for interventions that can be implemented. Patient & Public Involvement: This study is supported by the DIAMONDS (Diabetes and Mental Illness: Improving Outcomes and Services) research group (www.diamonds.nihr.ac.uk). The DIAMONDS PPI Panel has helped to prioritise the study questions and improve its design. They will remain involved throughout to help ensure we remain focused on the needs of people with SMI and their carers. Dissemination: To ensure that our study makes a difference, we will make findings available and accessible to people with SMI, and people who work and make decisions in the NHS. We will host an event to share results and discuss implications for diabetes care for people with SMI. We will also publicise findings via research publications, on our project website and across our mental health and diabetes networks.

Research activity codes: 7.1 INDIVIDUAL CARE NEEDS
Health categories: MENTAL HEALTH;METABOLIC AND ENDOCRINE