Aims. To study at greater than before material the prevalence of type 2 diabetes (DM2) in relatives of suffering from DM2 patients with cancer and compare the features of antidiabetic therapy in cancer patients with a familial and non-familial form of diabetes. Materials and Methods. Information about diabetes history in family was collected during two subsequent periods (May 2009-February 2011 and March 2011-July 2014 years) in cancer patients (totally,1955 people; 1351 of them with DM2 and 604 without diabetes), as well as in patients with DM2 without cancer (n=379). All patients answered questions about diabetes in their mothers, fathers, siblings, and other relatives. In cancer patients with DM2, data on the type of antidiabetic therapy for at least 6 months prior to enrolling into the hospital were collected. Results. A lower frequency of family diabetes in diabetic patients with cancer (28,5±1,2% vs 38,0±2,5%, p