Severe mental illness and quality of care for type 2 diabetes: A retrospective population-based cohort study

To compare quality of care for type 2 diabetes in people with severe mental illness (SMI) versus no mental illness.

We used routinely collected linked data to create a retrospective cohort study. We included 158,901 people diagnosed with type 2 diabetes in Scotland during 2009-2018 of whom 1701 (1%), 768 (0.5%) and 5211 (3%) had a prior hospital admission record for schizophrenia, bipolar disorder, and major depression, respectively. We compared recording of HbA1c, cholesterol, creatinine, blood pressure, urinary albumin, foot examination, retinopathy screening, body mass index and smoking during the first year after diabetes diagnosis using logistic regression and recording of HbA1c and retinopathy screening over longer follow-up using generalised linear mixed effects model, adjusting for confounding factors.

Receipt of care during the first year was generally similar, or better, for people with each SMI than for people without any mental illness. During mean follow up of 4.8 (SD 2.5) years, depression and bipolar disorder were associated with lower odds of receiving retinopathy screening.

Receipt of diabetes care was similar or better among people with SMI versus without SMI. However, mechanisms to support improved retinopathy screening for people with SMI are needed.