The US Food and Drug Administration (FDA) expanded the indication for 18 metformin-containing medications to include use in patients with impaired kidney function, making 40 to 50 percent of patients with type 2 diabetes (T2D) and poor kidney function eligible to take metformin.

The change to labelling will impact common diabetes drugs such as Actoplus Met (metformin and pioglitazone), Actoplus Met XR (metformin and pioglitazone, extended release), Avandamet (metformin and rosiglitazone), Fortamet (metformin extended release), Glucophage (metformin), Glucophage XR(metformin extended release), Glucovance (metformin and glyburide), Glumetza (metformin extended release), Invokamet (metformin and canagliflozin), Janumet (metformin and sitagliptin), Janumet XR(metformin and sitagliptin, extended release), Jentadueto (metformin and linagliptin), Kazano(metformin and alogliptin), Kombiglyze XR (metformin and saxagliptin, extended release), Prandimet(metformin and repaglinide), Riomet (metformin), Synjardy (metformin and empagliflozin), and Xigduo XR (metformin and dapagliflozin, extended release). These prescription-only drugs are used along with diet and exercise to lower blood glucose levels in patients with T2D.

Specific recommendations regarding the use of these drugs will also be provided to patients with impaired kidney function, the FDA said.

Currently, metformin use is not recommended in those with impaired kidney function to prevent lactic acidosis or excessive buildup of acid in the bloodstream, resulting in unusual pain and stomach discomfort in some patients. However, a recent review of studies on metformin by the FDA has shown that the drug can be safely used in patients with mild or moderately impaired kidney function, the agency said.

On top of the expanded indication, the FDA said the determination of whether a patient can take metformin should not merely rely on a single laboratory blood creatinine concentration test, rather on estimated glomerular filtration rate (eGFR) which is a more accurate measure of early kidney damage and status. It also takes into account other parameters such as patient age, gender, race, and weight that are of paramount importance.

“Patients should talk to their doctors if they have concerns about taking metformin,” according to a statement from the FDA. “Healthcare professionals on the other hand should follow the latest recommendations when prescribing metformin-containing medicines to patients with impaired kidney function.”

The change in the label now aligns the US labelling guidance with other countries and is a significant step forward for patients with T2D and mild or moderate chronic kidney disease (CKD) who otherwise have very limited options across diabetes treatments.