What is known and objective Polypharmacy and age are known to increase the risk for potential drug interactions. Type 2 diabetes has been associated with polypharmacy and several comorbidities. Currently, there is no information on whether the frequency of clinically relevant drug‐drug interactions and the risk for drug adverse effects differ between older persons with and without diabetes. The aim of this study was to investigate the frequency of drug‐drug interactions and the risk for drug adverse effects in these two groups in primary care. Methods The basic study population consisted of Finnish home‐dwelling primary care patients aged ≥ 65 years (N = 3039). For each person with diabetes, two controls were selected with adjusted age and gender. To collect data, electronic primary care patient records, a structured health questionnaire and a structured health examination conducted by a physician were utilized. Using the SFINX‐PHARAO® database, drug‐drug interactions and the risk for drug adverse effects were evaluated in 182 persons with type 2 diabetes and 176 persons without diabetes. Results and discussion There were no significant differences in the frequency of drug‐drug interactions or the risk for drug adverse effects in persons with and without diabetes. At least one clinically relevant interaction was found in 81 (44.5%) persons with diabetes and 73 (41.5%) persons without diabetes. The most common drugs causing interactions included non‐steroidal anti‐inflammatory drugs (NSAIDs) and warfarin. What is new and conclusion There is no difference in the frequency of drug‐drug interactions or risk for drug adverse effects in older home‐dwelling persons with and without diabetes. Due to common comorbidities and commonly used drugs among persons with diabetes, drug‐drug interactions involving warfarin or NSAIDs in particular should be carefully monitored to avoid drug adverse effects.