AimTo study the population-based prevalence of potentially inappropriate medication (PIM) among older individuals with diabetes, and to identify factors associated with their use. MethodsWe used the Quebec Integrated Chronic Disease Surveillance System (QICDSS) database to conduct a population-based cohort study of individuals with diabetes ≥66 years between April 1st, 2014 and March 31st, 2015. PIMs were defined according to the 2015 Beers Criteria. Factors associated with PIM use were identified using robust Poisson regression models. Risk ratios (RR) and 99% confidence intervals (99%CI) were calculated. ResultsMore than half (56%) of the 286,962 older individuals with diabetes used at least one PIM over a year. Benzodiazepines (41%), proton pump inhibitors (27%) and endocrine medication (mainly glibenclamide) (25%) were the most common PIMs used. Factors associated with PIM use included female sex (RR: 1.17; 99%CI: 1.16–1.18), and comorbidities such as schizophrenia (1.48; 1.45–1.51), anxiety disorders (1.34; 1.33–1.35) and Alzheimer's disease (1.14; 1.13–1.25). Risks of using PIMs increased both with increasing comorbidities and number of medications. ConclusionPIM use is highly prevalent among older individuals with diabetes. Interventions to promote optimal medication use should particularly target individuals with comorbidities and polypharmacy who are most vulnerable to adverse drug events.