The association between type 2 diabetes mellitus and bladder cancer risk among postmenopausal women.

INTRODUCTION: Evidence on the association between diabetes and risk of bladder cancer has been controversial. In addition, findings on the associations between duration of diabetes, diabetes treatment, and risk of bladder cancer have been inconsistent. METHODS: A total of 148,208 participants in Women's Health Initiative study were included. Information on diabetes status, diabetes duration, and treatment was collected both at baseline and during follow-up. Information on potential confounders including age, race/ethnicity, education, occupation, family history of cancer, smoking status, alcohol consumption, total physical activity, body mass index, and daily dietary intake were collected at baseline. Bladder cancer cases were collected and confirmed by a centralized review of pathology reports. Cox proportional hazard models with time-varying covariates were used to examine associations of diabetes status, duration of diabetes, and diabetes treatment with bladder cancer risk. RESULTS: During a median follow-up of 18.5 years, 865 bladder cancer cases were identified. There were no significant associations of diabetes, duration of diabetes, or diabetes treatment with risk of bladder cancer. Participants with prevalent diabetes did not have significantly higher risk of bladder cancer compared with those without diabetes. CONCLUSION: Diabetes was not significantly associated with risk of bladder cancer among postmenopausal women.