INS and type 2 diabetes mellitus: Moreover, metformin has attracted interest as an anti-cancer drug [27], since an association between metformin use in type 2 diabetes mellitus (T2DM) patients and a reduced risk of breast, colon, pancreas and prostate cancer was found [28,29,30,31,32,33], as well as a reduced risk of mortality, as compared with patients treated with insulin or sulfonylureas [34].