Purpose of review This paper reviews research on substance use and disorders (SUDs) among adults with diabetes. It describes epidemiological data on SUDs in persons with type 2 diabetes, overviews effects of substance use on diabetes outcomes, and discusses treatments for SUDs in patients with diabetes. Recent findings Rates of current smoking range from 10 to 26% and alcohol use disorders are 0-5%. Rates of illicit SUDs are 3-4%, but there are no population-based studies using nationally representative samples. Smoking increases the risk for long-term diabetes complications and premature death. Alcohol and illicit drug use can also impact long-termdiabetes complications by impairing glucose homeostasis and adversely influencing self-management behaviors. There is mixed evidence about psychosocial smoking cessation interventions in adults with diabetes and little on alcohol and illicit SUD interventions. Limited data exist on pharmacotherapies for SUDs in this population, but a recent study suggests that varenicline is safe and effective for treating smoking in patients with diabetes. Summary Substance use is an understudied problem in type 2 diabetes, and addressing substance use holds potential for improving outcomes. Additional large population-based epidemiological studies in those with type 2 diabetes are needed, particularly for alcohol and illicit SUDs. Longitudinal studies should be conducted to better understand the time course of diabetes onset and outcomes in relation to SUDs. Randomized controlled trials are needed to assess safety and efficacy of promising psychosocial and pharmacological interventions.