Cardioprotective Effects of Metformin

Metformin, routinely used as first-line drug in the treatment of type 2 diabetes, has been shown to have cardioprotective effects beyond its glycemic control. These have been attributed to increases in Akt concentrations and activation of protein kinases in the RISK pathways, which prevent the mPTP from opening and rupturing it and therefore, protects myocyte viability. In myocardial infarction and subsequent reperfusion, metformin activation of AMPK promotes glycolysis and keeps the mPTP closed. Given as a preconditioning and/or postconditioning agent, metformin has been shown to decrease infarct size and improve survival rates after myocardial infarction. Metformin has further been reported to restore depleted PGC-1α levels and improve mitochondrial biogenesis by increasing phosphorylation of eNOSser1177, which produces NO and leads to reduced vascular inflammation and myocardial injury after ischemia. There is strong evidence suggesting that metformin improves cardiovascular outcomes by influencing metabolic signal transduction pathways. There are growing calls for metformin use to be expanded off-label beyond the traditional glycemic control. We review experimental evidence for metformin's impact on cardiovascular disease and its underlying molecular mechanisms of action and also discuss why significant gains made in experimental conditions have not translated into significant therapeutic applications.