Atrial fibrillation is one of the most common concomitant diseases in patients with diabetes mellitus (DM). Meta-analyses of multiple studies have shown that the risk of AF is higher for diabetic patients with impaired glucose homeostasis than for patients without DM. Patients with AF and DM were younger, more frequently had arterial hypertension, chronic kidney disease, heart failure, and ischemic heart disease, and stroke and were characterized with a more severe course of AF. The article discusses possible mechanisms of the mutually aggravating effects of DM and AF, scales for evaluating the risk of bleeding (CHADS2, CHA2DS2‑VASc, HAS-BLED), and the role of anticoagulants. A meta-analysis of 16 randomized clinical studies, including 9 874 patients, has demonstrated the efficacy of oral anticoagulants in prevention of stroke with an overall decrease in the relative risk by 62 % compared to placebo (95% confidence interval, from 48 to 72 ). For prevention of complications in patients with AF and DM, current antithrombotic therapies can be used, specifically the oral factor Xa inhibitor, rivaroxaban, which is the best studied in patients with AF and DM and represents a possible alternative to warfarin in such patients.