Association of metformin use with risk of lactic acidosis across the range of kidney function

Metformin hydrochloride is the preferred first-line treatment for type 2 diabetes, but the medication is withheld from a large swath of this patient population.

Metformin hydrochloride is the preferred first-line treatment for type 2 diabetes, but the medication is withheld from a large swath of this patient population. Largely because of the fear of acidosis, metformin is often not recommended for patients with an estimated glomerular filtration rate (eGFR) below 60 mL/min/1.73 m2—which is a marker for chronic kidney disease. Researchers performing a retrospective analysis tracked the correlation between eGFR and acidosis in about 75,400 type 2 diabetics, taking into account eGFR changes over a period of 13 years. They found no significant association between metformin use and acidosis in patients with eGFR levels in the range of 30–60 mL/min/1.73 m2. The results were replicated in a second cohort comparing acidosis outcomes in nearly 67,600 new metformin users with those of about 14,400 new sulfonylurea users. The findings suggest that patients with concomitant diabetes and kidney disease may safely take metformin if they maintain an eGFR of at least 30mL. Regulatory and professional society guidelines are starting to bend to accommodate evidence supporting metformin use in diabetics with moderate to mild kidney disease—among them, FDA, which recently changed the drug's label to allow more wiggle room for treating patients with eGFR of at least 45 mL/min/1.73 m2.