Background Among people with type 2 diabetes (T2D), those with comorbid serious mental illness (SMI) are at increased risk of diabetes complications and early death, which could be related to quality of diabetes care. We therefore sought to compare the receipt of diabetes care in people with and without SMI in the first year after T2D diagnosis and in the longer term.

Methods Using national Scottish population-based records, we included 119,508 people with T2D diagnosed from 2009 – 2018 and ascertained those with a prior hospital record of schizophrenia, bipolar disorder, or depression. The outcomes were annual assessment of each of HbA1c, cholesterol, urinary albumin, serum creatinine, blood pressure, retinopathy screening, foot examination, body mass index, smoking status, and overall care (having received all measures). We compared receipt of each measure in the first year after diabetes diagnosis in people with and without each SMI using logistic regression. We then compared receipt of HbA1c (a marker of measures routinely measured in the primary care setting) and retinopathy every year post diagnosis to end of follow-up (31.12.2018) using generalized linear mixed effect models. Analyses were adjusted for age, sex, calendar year, diabetes duration, area-based deprivation, ethnicity, urbanicity, health board, smoking and history of alcohol disorder, CVD, and other comorbidities.

Results People with SMI (n=7,680) were more likely to: be younger; be white; live in deprived areas; have a history of alcohol use disorder, CVD, and comorbidities; and be smokers. Compared to people without a SMI those with schizophrenia, bipolar disorder and depression had a lower odds of receiving urinary albumin tests, retinopathy screenings and overall care and a higher odds of receiving cholesterol and serum creatinine measurements in the first year after diabetes diagnosis. Receipt of the other measurements were similar in each group. In the longitudinal analysis, receipt of retinopathy remained lower in those with versus without each SMI, but there was no difference in receipt of HbA1c.

Conclusion Receipt of most processes of care was similar in people with and without SMI during the first year post-diabetes diagnosis and in the longer term. However, people with SMI were less likely to have urinary albumin checked and retinopathy screening. This indicates that there is scope to improve receipt of these diabetes monitoring measures among people with SMI.