(HealthDay News) — For individuals with impaired kidney function, evidence suggests that metformin use is safe in those with mild or moderate disease, according to a review published in the Dec. 24/31 issue of the Journal of the American Medical Association.

Silvio E. Inzucchi, M.D., from the Yale University School of Medicine in New Haven, Conn., and colleagues conducted a systematic review involving 65 articles to examine the risk of lactic acidosis associated with metformin use in diabetes patients with impaired kidney function.

The researchers found that metformin levels generally remained within the therapeutic range although the drug was renally cleared; in patients with mild to moderate chronic kidney disease (estimated glomerular filtration rates, 30 to 60 mL/min/1.73 m²), lactate concentrations were not increased substantially. 

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Across studies, the overall incidence of lactic acidosis in metformin users varied from approximately three to 10 per 100,000 person-years, and was generally indistinguishable from the background rate among those with diabetes. 

Limited data suggest an increased risk of lactic acidosis in metformin-treated patients with chronic kidney disease, but the safety of metformin in patients with significantly impaired kidney function has not been examined in randomized controlled trials. A potential benefit of metformin on macrovascular outcomes was seen in observational studies, even among patients with prevalent renal contraindications for use.

“Available evidence supports cautious expansion of metformin use in patients with mild to moderate chronic kidney disease, as defined by estimated glomerular filtration rate, with appropriate dosage reductions and careful follow-up of kidney function,” the authors write.

Several authors disclosed financial ties to pharmaceutical companies.


  1. Inzucchi, SE, et al. JAMA, 2014; doi:10.1001/jama.2014.15298