Abstract: The incidence of malignancy tumors has increased significantly recent years in patients with type 2 diabetes mellitus (T2DM). As the first- line oral medicine of T2DM, in addition to the safe and effective hypoglycemic effect,metformin can reduce the incidence and mortality of cancer, and improve the prognosis in T2DM patients. While the exactly anti- tumor mechanisms of metformin is not yet clear, which might be the inhibition of proliferation and promotion of apoptosis of tumor cells mainly by acting on an adenosine monophosphate activated protein kinase (AMPK) and microRNAs(miRNAs). And metformin can inhibit migration and invasion of tumor cells, as well as strengthen the effects of chemotherapy drugs. This article reviews the recent research progress of clinical and epidemiological studies and anticancer mechanisms of metformin.

Key words: metformin, neoplasms, diabetes mellitus, type 2, cell proliferation, apoptosis, microRNAs, rewiew, adenosine monophosphate activated protein kinase