Metformin Relabeling Would Boost Use Among Type 2 Diabetics

Although metformin is a proven first-line diabetes medication, many patients with type 2 diabetes (T2D) are discouraged from taking the drug due to inappropriate FDA labeling, according to a research letter published on January 5, 2015, in JAMA Internal Medicine.

A pair of researchers from Weill Cornell Medical College and the University of Pennsylvania discovered that the FDA currently labels metformin as unsafe for use in some T2D patients with comorbid kidney problems. The study authors believe that this label is overly conservative and differs immensely from professional society recommendations, such as those of the American Diabetes Association (ADA).

In the research, 2007 to 2012 data from the National Health and Nutrition Survey was examined alongside serum creatinine levels and estimated glomerular filtration rates (eGFRs) to determine how much metformin non-use was attributable to safety concerns.

According to the authors, T2D patients with eGFRs >60 to 90 mL/min, which indicate mild renal function impairment but fall below the FDA’s contradiction cutoff, used metformin at a rate of roughly 80.6%. However, those with eGFRs between 30 and 60 mL/min—the levels at which professional societies and the FDA differ in opinion—used metformin at rates between 48% and 57%. If the FDA amended the drug’s label, then an additional 1 million T2D patients—including those with kidney problems—would receive the drug, the researchers contended.

“Pharmacists and patients should be aware that common prescribing practices are too conservative and lead to under-use of metformin in patients with mild to moderate kidney disease. In fact, metformin is still safe in many of these patients and remains a superior option for treating T2D,” study co-author James H. Flory, MD, MSCE, told Pharmacy Times. “A position statement from the ADA supports use of metformin in patients with a eGFR >30 mL/min, which corresponds to moderate chronic kidney disease.”

The researchers noted that citizen petitions were filed against the FDA in 2012 and 2013 to request that the labeling requirements for metformin be relaxed and redefined in terms of more modern eGFR measures. The FDA, however, has not yet responded to those petitions.

“The FDA is overdue to revisit the contraindication to metformin use in patients with mild to moderate renal insufficiency, which is worsening the care of almost 1 million patients with T2D in the US,” the study authors concluded.