Diabetes Mellitus Reduces Prostate Cancer Risk - No Function of Age at Diagnosis or Duration of Disease

Background: Prior studies examining the relation between diabetes mellitus (DM) and prostate cancer riskhave reported controversial findings. We examined this association by conducting a detailed meta-analysis of thepeer-reviewed literature.
Methods: A comprehensive search for articles of MEDLINE and EMBASE databasesand bibliographies of retrieved articles published up to November, 2012 was performed. Methodological qualityassessment of the trials was based on the Newcastle-Ottawa Scaleq and the meta-analysis was performed usingSTATA 12.0. Dose-response regression was conducted with SPSS 19.0.
Results: We included 29 studies in themeta-analysis (13 case-control studies, 16 cohort studies), and found an inverse association between DM andprostate cancer (relative risk (RR) 0.84, 95% confidence interval (CI), 0.78-0.91). An inverse association wasalso observed in non-Asian populations (RR 0.81, 95% CI 0.76-0.87) and population-based studies (RR 0.80,95% CI 0.77-0.91). No statistical significance was found of the association between prostate cancer risk and theduration of DM (p=0.338), and risk seemed not related with the age of DM diagnosis.
Conclusions: This studysuggested an inverse relationship between DM and prostate cancer, but without links to duration of disease orage of diagnosis.