INS and cancer: Several studies have revealed that metformin (N,N-dimethylbiguanide) (Figure 1) [11], which is a crucial anti-diabetic drug discovered by the French physician Jean Sterne [12], has an anti-tumorigenic impact on cancer cells through several mechanisms, including the indirect mechanism (insulin-dependent), in which metformin activates AMPK, which leads to the decrease of the gluconeogenesis process and the increase of glucose uptake in muscle cells, thereby resulting in the reduction of the blood glucose level and the insulin level.