Orloff J, Min JY, Mushlin A, et al. - In this systematic review, researchers sought to explore clinical and safety outcomes associated with metformin use in patients with impaired renal function, defined as an estimated glomerular filtration rate [eGFR] < 60 ml/min/1.73m ². They included any study that reported original data on metformin and patient-centered outcomes in patients with impaired renal function. Post-hoc meta-analysis was conducted for the outcomes of mortality, cardiovascular events, and acidosis. According to the literature, metformin is associated with lower mortality and no increased risk of acidosis at eGFR ≥ 45 ml/min/1.73m ². Metformin appears to provide fewer benefits and may increase the risk of acidosis at eGFR < 30 ml/min/1.73m ². Metformin should not be used at eGFR < 30 ml/min/1.73m ², according to FDA guidelines, and more research on its risk-benefit profile at eGFRs approaching 30 is needed.