Still sour about lactic acidosis years later: role of metformin in heart failure

Metformin remains a widely-used, first-line pharmacotherapy agent for patients with type 2 diabetes mellitus because of its efficacy, mild side effects, and affordability. However, use of this medication has traditionally been shunned by clinicians in patient populations that are considered at risk of lactic acidosis, such as those with heart failure. The underutilization of metformin can largely be attributed to the historical stigma of its biguanide predecessor, phenformin, and its association with lactic acidosis. Despite various studies finding low rates of lactic acidosis and the United States Federal Drug Administration’s subsequent removal of heart failure from metformin’s contraindication labeling in 2006, this oral hypoglycemic remains underutilized in this patient population. In addition to reports of the safe use of metformin in the heart failure population, a multitude of studies have also additionally suggested a modest reduction in mortality and morbidity. Metformin’s role should be strongly reconsidered in the armamentarium of diabetes management in heart failure patients.