(HealthDay News) — Despite smaller, prior studies suggesting that pioglitazone might raise users’ risk for bladder cancer, a large new study finds no statistically significant association. 

The research was published in the Journal of the American Medical Association.

Certain prior studies had suggested an increased risk of bladder cancer with the use of pioglitazone. A team led by Assiamira Ferrara, MD, PhD, of Kaiser Permanente Northern California in Oakland, examined long-term data from 193,099 diabetes patients.

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There appeared to be no statistically significant association between taking the medication and increased risk for bladder cancer, the researchers found. However, a small increased risk could not be ruled out. 

The researchers also analyzed long-term data from another group of 236,507 patients with diabetes and found that taking pioglitazone was associated with a 41% increased risk for pancreatic cancer and a 13% increased risk for prostate cancer.

“Pioglitazone use was not associated with a statistically significant increased risk of bladder cancer, although an increased risk, as previously observed, could not be excluded,” the researchers wrote. 

“The increased prostate and pancreatic cancer risks associated with ever use of pioglitazone merit further investigation to assess whether they are causal or are due to chance, residual confounding, or reverse causality.”

The study was funded by Takeda, which manufactures pioglitazone.


  1. Lewis JD et al. JAMA. 2015;314(3):265-277.