Glucose-lowering medication prescribing patterns among people with mental illness and diabetes

Precision Medicine Project - Glucose-lowering medication prescribing patterns among people with mental illness and diabetes

Supervisor(s): Dr Caroline Jackson, Prof Sarah Wild & Dr Sofia Carlsson (Karolinska Institutet)
Centre/Institute: Usher Institute

Background

Mental illness (including, but not limited to depression, bipolar disorder, schizophrenia and other psychoses) is common among people with type 2 diabetes. Compared to the general population, people with mental illness have a two-fold higher risk of diabetes.1 Moreover, compared to those without mental illness, they develop diabetes at an earlier age and have considerably higher risk of poor outcomes, such as cardiovascular disease and other complications.2,3 Reasons for this remain poorly understood, with associations not fully explained by known confounders or potential mediators, and a lack of randomized evidence on diabetes drug treatment effects due to the exclusion of people with mental illness from trials. Optimal diabetes management, including recently developed precision treatment approaches4, minimises risk of diabetes complications, but our understanding of the quality of diabetes care in underserved populations, including those with mental illness, is limited. We do not know how timeliness of treatment and choice of medication differs by mental illness status and whether there is equitable access to treatment among patient sub-groups. This cross-country study leverages data from the UK (the Clinical Practice Research Datalink (CPRD) resource) and Sweden (a Swedish nationwide dataset with treatment, mental health, and sociodemographic information from registers with near-complete coverage, crucial for studying vulnerable groups), to investigate to what extent glucose-lowering medication (GLM) prescribing in type 2 diabetes varies by mental illness status. We will analyse time to drug initiation, intensification and discontinuation, and treatment transition patterns, by mental illness status, accounting for whether mental illness occurs pre- or post-diabetes diagnosis. We will identify factors influencing treatment decisions, including routinely available factors that have been identified to affect treatment response (e.g. in https://www.diabetesgenes.org/t2-treatment))4.

Aims

  1. Determine to what extent GLM prescribing differs by mental illness status (defined as a composite variable and as individual disorders) through analysis of time to initiation, intensification of treatment, patterns of drug choice and discontinuation
  2. Identify factors that influence prescribing of GLM and blood pressure- and lipid-lowering medication in people with mental illness, including age, sex, ethnicity, routine factors identified as affecting treatment response (e.g. BMI, smoking status and baseline HbA1c), psychotropic medication, polypharmacy and prescriber preferences
  3. Compare GLM prescribing by mental illness status in the UK and Sweden 

Training outcomes

This PhD provides the student with a unique skill-set encompassing epidemiology, pharmaco-epidemiology, advanced statistics and the use of large, complex linked data in research, with application to diabetes and mental health research, a well-recognised area of population health importance. The project includes an international exchange, allowing the PhD student to visit Karolinska Institutet in Stockholm to work with Swedish data. The student will obtain valuable experience in interacting with a range of academic, clinical and public health practice/policy colleagues. They will also engage in PPIE activities, through established links with relevant PPIE groups formed by the UoE supervisory team. This experience of working with a diverse group of people will equip them with essential transferable skills and interdisciplinary engagement necessary for career development. 

We will work with the student to develop a tailored training plan, which could include training in pharmacoepidemiology (via short courses offered by the London School of Hygiene and Tropical Medicine, R software (through the University of Edinburgh MSc Epidemiology programme, or the HDRUK R course), statistical techniques such as multi-state modelling and instrumental variable analysis, causal inference and PPIE. They will benefit from training in generic research skills and transferrable skills through the Institute of Academic Development. The student will be expected and supported to present their work to lay and professional audiences and submit articles to international peer-reviewed journals.

References

  1. Vancampfort D, Correll CU, Galling B, et al. Diabetes mellitus in people with schizophrenia, bipolar disorder and major depressive disorder: a systematic review and large scale meta-analysis. World Psychiatry 2016; 15(2): 166-74.
  2. Fleetwood KJ, Wild SH, Licence KAM, Mercer SW, Smith DJ, Jackson CA. Severe Mental Illness and Type 2 Diabetes Outcomes and Complications: A Nationwide Cohort Study. Diabetes Care 2023; 46(7): 1363-71.
  3. Scheuer SH, Kosjerina V, Lindekilde N, et al. Severe Mental Illness and the Risk of Diabetes Complications: A Nationwide, Register-based Cohort Study. J Clin Endocrinol Metab 2022; 107(8): e3504-e14.
  4. Dennis, John M et al. A five-drug class model using routinely available clinical features to optimise prescribing in type 2 diabetes: a prediction model development and validation study. The Lancet, 2025: Volume 405; Issue 10480, 701 - 714

Apply Now

Click here to Apply Now

  • The deadline for 26/27 applications is Monday 12th January 2026
  • Applicants must apply to a specific project. Please ensure you include details of the project on the Recruitment Form below, which you must submit to the research proposal section of your EUCLID application.
  • Please ensure you upload as many of the requested documents as possible, including a CV, at the time of submitting your EUCLID application.  

Q&A Sessions

Supervisor(s) of each project will be holding a 30 minute Q&A session in the first two weeks of December. 

If you have any questions regarding this project, you are invited to attend the session on TBC via Microsoft Teams. Click here to join the session.

This article was published on