Drug-drug interactions in diabetic patients could be serious, even life threatening. Possible manifestation of hypo/hyperglycemia as a consequence of drug-drug interactions are often wrong interpreted as a nonadherence to the diabetic diet or polymorbidity of the patient. Drug-drug interactions are not taken into account. The risk of drug-drug interactions is exponentially increasing with the number of taken drugs. In the group of diabetic patients is good to prevent the combinations of drugs, which can lead to drug-drug interactions and use alternative therapy with lower potential of drug-drug interactions. In this paper we present the possibilities of clinical pharmacist from the Department of clinical pharmacology to prevent and solve the drug-drug interactions in diabetic patients.