Comorbid Diabetes and Severe Mental Illness: Outcomes in an Integrated Health Care Delivery System

Background Diabetes prevalence is twice as high among people with severe mental illness (SMI) when compared to the general population. Despite high prevalence, care outcomes are not well understood. Objective To compare diabetes health outcomes received by people with and without comorbid SMI, and to understand demographic factors associated with poor diabetes control among those with SMI. Design Retrospective cohort study Participants 269,243 adults with diabetes Main Measures Primary outcomes included optimal glycemic control (A1c < 7) or poor diabetes control (A1c > 9) in 2014. Secondary outcomes included control of other cardiometabolic risk factors (hypertension, dyslipidemia, smoking) and recommended diabetes monitoring. Key Results Among this cohort, people with SMI (N = 4,399), compared to those without SMI (N = 264,844), were more likely to have optimal glycemic control, adjusting for various covariates (adjusted relative risk (aRR) 1.25, 95% CI 1.21-1.28, p < .001) and less likely to have poor control (aRR 0.92, 95% CI 0.87-0.98, p = 0.012). Better blood pressure and lipid control was more prevalent among people with SMI when compared to those without SMI (aRR 1.03; 95% CI 1.02-1.05, p < .001; aRR 1.02; 95% CI 1.00-1.05, p = 0.044, respectively). No differences were observed in recommended A1c or LDL testing, but people with SMI were more likely to have blood pressure checked (aRR 1.02, 95% CI 1.02-1.03, p < .001) and less likely to receive retinopathy screening (aRR 0.80, 95% CI 0.71-0.91, p < .001) than those without SMI. Among people with diabetes and comorbid SMI, younger adults and Hispanics were more likely to have poor diabetes control. Conclusions Adults with diabetes and comorbid SMI had better cardiometabolic control than people with diabetes who did not have SMI, despite lower rates of retinopathy screening. Among those with comorbid SMI, younger adults and Hispanics were more vulnerable to poor A1c control.