Lactic Acidosis, Metformin Use, and Dose-Response Association

To the Editor In a recent issue of JAMA Internal Medicine, Lazarus and colleagues¹ investigated the relationship between metformin treatment and lactic acidosis across different categories of estimated glomerular filtration rate (eGFR) in 2 large community-based cohorts of patients with diabetes. They did not observe an increased risk of incident hospitalization with lactic acidosis in metformin users with eGFR greater than 30 mL/min/1.73 m² compared with patients who received alternative diabetes management. However, there was an excess risk of lactic acidosis in metformin users with eGFR less than 30 mL/min/1.73 m².