Familial diabetes is associated with reduced risk of cancer in diabetic patients: a possible role for metformin.

Type 2 diabetes mellitus (DM2) is a risk factor of a number of malignancies. Therefore, it is important to identify factors linking DM2 and cancer within family units and how current treatment regimens influence the development of cancer in DM2 patients. The present case-controlled study was designed to assess DM2 prevalence among parents or siblings of (a) cancer patients who did not have diabetes (n = 77; age 59.