Metformin is an orally administered biguanide derivative used to lower blood glucose concentrations in patients with non-insulin-dependent diabetes mellitus. It improves insulin sensitivity and decreases insulin resistance by inhibiting Complex 1 of the mitochondrial respiratory chain and inducing AMP-activated protein kinase-dependent signaling. At 50-400 mg/kg body weight, metformin can stimulate glucose uptake in skeletal muscle and suppress hepatic gluconeogenesis in B6-Lepob/ob mice. Metformin has also been shown to improve fatty liver disease by reversing hepatic steatosis in ob/ob mice, restoring ovarian function in polycystic ovary syndrome, and directly inhibiting tumor growth in cancer cell lines.
