Reduced risk of prostate cancer in a cohort of Lithuanian diabetes mellitus patients

Abstract

Background During the past decade, a huge interest was devoted to the type-2 diabetes mellitus and their associations with prostate cancer development. Objectives The aim of this study was to determine whether type 2 diabetes mellitus and treatment with metformin is associated with prostate cancer risk. Materials and methods The cohort was composed of diabetic male patients identified in the National Health Insurance Fund database during 2000–2016 and cancer cases in national Cancer Registry. We calculated standardized incidence ratios (SIR) for prostate cancers as a ratio of observed number of cancer case in people with diagnosis of diabetes to the expected number of cancer cases in the underlying general population. Results 2754 prostate cancers were observed versus 3111.26 expected within the period of observation entailing an SIR of 0.89 (95% CI: 0.85–0.92). Significantly lower risk of prostate cancer was found in diabetes patients in all age groups, also was in metformin-users and never-users’ groups, with higher risk reduction in metformin-users (SIR 0.71, 95% CI: 0.68–0.75) than in diabetes patients never-users (SIR 0.88, 95% CI: 0.80–0.96). Conclusion In this large population-based study, we found a significantly decreased risk of prostate cancer among men with diabetes and metformin-users.