Patients with type 2 diabetes who take pioglitazone, especially those who take it for more than two years, may be more likely to develop bladder cancer than those who have never taken the drug. That's according to the results of a study conducted by Canadian researchers that was published May 31 in . The researchers also found that the increased risk of bladder cancer seen with pioglitazone use was not observed with use of its thiazolidinedione sibling rosiglitazone, confirming a drug-specific effect. "Furthermore, a dose-response relation was observed for cumulative duration of use, with the highest risk observed in participants who used pioglitazone for more than 24 months," the authors note. "A similar dose-response relation was observed in patients who received a high cumulative dosage of pioglitazone."