OBJECTIVE: Create a taxonomy and examine the predictors of the often co-occurring conditions of substance use disorders and mental illness in veterans with diabetes.

DESIGN: Merged Veteran Health Administration and Medicare fee-for-service claims data (N = 485,893).

RESULTS: Thirty-one percent of patients with diabetes were diagnosed with either mental illness or substance use and had higher rates of diabetes-related complications. Women were more likely to have serious mental illness; African Americans and Latinos more likely to have drug and/or alcohol use.

CONCLUSION: Prevalence of substance use disorder and mental illness differed by socio-demographics, suggesting the need for tailored diabetes management interventions.