FDA Expands Metformin Label

— The diabetes drug can now be used in more patients with reduced kidney function

The FDA on Friday greatly expanded the indication for the type 2 diabetes drug metformin. Until now use of metformin in patients with reduced kidney function had not been recommended. The new label states that metformin “can be used safely in patients with mild impairment in kidney function and in some patients with moderate impairment in kidney function.”

In addition the label will now recommend that kidney function be assessed using  estimated glomerular filtration rate (eGFR), thereby replacing the use of serum creatinine . eGFR “takes into account additional parameters that are important, such as the patient’s age, gender, race and/or weight,” the FDA said.

“This is huge news in the diabetes space,” said Darren McGuire, UT Southwestern. The change “now aligns the US labeling guidance with most of the rest of the world.” He estimated that this change means that “40% or 50% of patients with type 2 diabetes who have mild-moderate CKD” will now be eligible to take metformin.

McGuire said that he was a a co-signer on one of two separate citizen petitions filed with the FDA two years ago requesting this change. It “took a long time but the agency seems to have gotten it just right in these revised cautions for patients with impaired kidney disease.”

“I think this is a big step forward and a win for patients with diabetes and mild/moderate CKD,” he said, because these patients are at increased cardiovascular risk. This change allows “the number one recommended treatment” for use in the highest risk patients who otherwise have “quite limited options across DM therapies.” Metformin is the cornerstone of therapy with other drugs, said McGuire. Other diabetes drugs should be used instead if metformin is contraindicated or not tolerated.

Metformin, said McGuire, “is cheap, well tolerated and the best available evidence supports modest but consistent estimates for cardiovascular efficacy.” He said he also supports the switch from the “anachronistic use of creatinine thresholds to contemporary use of eGFR allowing for more ‘precision’ medical decision making.”

An eGFR should be obtained at least once a year for all patients taking metformin, and more often in patients at increased risk for renal impairment, the FDA said.

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