OBJECTIVES : Patients with diabetes are at high risk for polypharmacy (i.e. use of multiple classes of medications) for treatment of diabetes, associated comorbidities, and other co-existing conditions. This study aims to estimate the prevalence of polypharmacy and factors associated with polypharmacy among adult patients with diabetes. METHODS : A cross-sectional retrospective observational study of adults with diabetes, who visited the outpatient clinic of a tertiary teaching hospital in Saudi Arabia, was conducted. Data were extracted from the Electronic Health Record (EHR) database for a period of twelve-month (January to December 2016). Polypharmacy was defined as the cumulative use of five or more medication classes. Polypharmacy among adults with diabetes was measured by calculating the average number of medication classes prescribed per patient. A multivariable logistic regression model was used to examine the factors associated with polypharmacy after adjusting for age, sex, marital status, nationality, and co-existing chronic conditions. RESULTS : A total of 8,932 adults with diabetes were included in this study. Of these, nearly 78 % had polypharmacy, which was more likely among women as compared to men and more likely among the elderly (age >