[New promises for metformin: advances in the understanding of its mechanisms of action].

Metformin is currently the drug of first choice for the treatment of type 2 diabetes. However, although prescribed since the end of the 1950s, the mechanism of action of metformin remains as yet incompletely understood but recent work has unveiled novel and surprising properties. Epidemiological reports have suggested that metformin protects against heart failure and has antitumor properties independent of its anti-hyperglycemic effect. Here, we review the proposed mechanisms for metformin action in diabetes, cardiovacular diseases and cancer.