Safety and effectiveness of metformin in patients with reduced renal function: A systematic review.

The literature shows metformin to be associated with reduced mortality and no increased risk of acidosis at an eGFR of 45 mL/min/1.73m2 or higher. Metformin appears to be associated with fewer benefits and possible increases in the risk of acidosis at an eGFR of less than 30 mL/min/1.73m2 . Consistent with US Food and Drug Administration guidelines, metformin should not be used at an eGFR less than 30 mL/min/1.73m2 , and further research on its risk-benefit profile at eGFR values approaching 30 mL/min/1.73m2 is warranted.