Between 2004 and 2009, more than half a million adverse reactions among people taking anti-diabetic drugs were added to an official U.S. Food and Drug Administration database. Among those reports were 138 instances of bladder cancer in patients taking at least one of more than 15 different anti-diabetic drugs.
However, more than a fifth of those bladder cancers were in patients taking Actos (pioglitazone), suggesting a "disproportionate risk" in comparison with other anti-diabetics, said study author Dr. Elisabetta Poluzzi of the University of Bologna in Italy.
The article is: "Assessing the Association of Pioglitazone Use and Bladder Cancer Through Drug Adverse Event Reporting" and may be found here.
Here is the abstract:
OBJECTIVE To analyze the association between pioglitazone use and bladder cancer through a spontaneous adverse event reporting system for medications.
RESEARCH DESIGN AND METHODS Case/noncase bladder cancer reports associated with antidiabetic drug use were retrieved from the U.S. Food and Drug Administration (FDA) Adverse Event Reporting System (AERS) between 2004 and 2009 and analyzed by the reporting odds ratio (ROR).
RESULTS Ninety-three reports of bladder cancer were retrieved, corresponding to 138 drug-reaction pairs (pioglitazone, 31; insulin, 29; metformin, 25; glimepiride, 13; exenatide, 8; others, 22). ROR was indicative of a definite risk for pioglitazone (4.30 [95% CI 2.82–6.52]), and a much weaker risk for gliclazide and acarbose, with very few cases being treated with these two drugs (6 and 4, respectively).
CONCLUSIONS In agreement with preclinical and clinical studies, AERS analysis is consistent with an association between pioglitazone and bladder cancer. This issue needs constant epidemiologic surveillance and urgent definition by more specific studies.