Meta-Analysis IDs Link Between Type 1 Diabetes and Bladder Cancer

MONDAY, Dec. 1, 2025 (HealthDay News) — Type 1 diabetes is associated with bladder cancer, according to a study published in the December issue of Diabetes Research and Clinical Practice.

Helena Oskoui Bennett, M.P.H., from the University of Southern California Keck School of Medicine, and colleagues conducted a systematic review to examine the role of type 1 diabetes in bladder cancer. Nine independent studies were identified; eight of these studies had not addressed confounding by history of tobacco smoking.

The quantitative synthesis of original data was implemented by meta-regression to detect and quantify residual confounding by smoking tobacco; a synthetic meta-analysis was then conducted to combine smoking-controlled estimates. The researchers identified a fourfold increased occurrence of bladder cancer in those with type 1 diabetes (summary estimate, 4.29 based on nine studies) in this analysis.

“Of nine original studies and one meta-analysis published before ours, none had adequately controlled for smoking,” senior author Victoria K. Cortessis, Ph.D., also from the Keck School of Medicine, said in a statement. “When we evaluated the vulnerabilities of these studies and addressed them, we found a very clear pattern indicating substantially elevated risk for bladder cancer in people with type 1 diabetes.”

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