Following a fresh review of studies on the safety of type 2 diabetes medication pioglitazone, the U.S. Food and Drug Administration (FDA) has reaffirmed its warnings that the drug may be linked to an increased risk of bladder cancer.

Medicines containing pioglitazone (Actos, Actoplus Met, Actoplus Met XR, Duetact, and Oseni) already feature warnings about the risk, but the FDA will update the label to include the additional studies it reviewed to support its decision.

Pioglitazone is a prescription drug designed to improve blood sugar control by increasing the body’s sensitivity to insulin.

The FDA originally alerted the public to the association between pioglitazone and bladder cancer in September 2010 based on interim results of a 10-year epidemiologic study. The regulatory agency then updated the label for the drug in August 2011 to include a warning of bladder cancer risk. Takeda Pharmaceuticals, the maker of the drug, was directed to modify and continue the 10-year study.

The final results of the 10-year study compared 158,918 patients who never took the drug to 34,181 patients who had taken pioglitazone. The findings concluded that there was no increased risk of bladder cancer in patients who took pioglitazone. A separate European study published in Diabetologia also found no link between the drug and bladder cancer.

Despite these studies that found no association, the FDA stood by its warnings based on other published studies with conflicting results.

“We systematically reviewed published epidemiological studies evaluating the risk of bladder cancer with pioglitazone use,” the FDA wrote in its safety announcement Monday. “Some studies found an increased risk of bladder cancer with pioglitazone use and others did not.”

An overall look at the data still suggests pioglitazone may be linked to an increased risk of bladder cancer, the FDA added.

Patients who take pioglitazone are urged to contact their health care professionals if they experience blood in the urine, pain when urinating, and a new or worsening urge to urinate.