BACKGROUND: Studies of the impact of type 2 diabetes on the prevalence and incidence of lower urinary tract symptoms (LUTS) among men have provided divergent results. We sought to examine this issue using two large and diverse cohorts. METHODS: This study used questionnaire and clinical data from two large multiethnic cohorts, the California Men’s Health Study (CMHS) and Research Program in Genes, Environment and Health (RPGEH). Diabetes characteristics data were derived from questionnaire and Diabetes Registry data. LUTS were measured using a standardized scale. Socioeconomic and comorbidity data were obtained by self-report. Multivariable logistic regression analysis was used to examine the association between baseline DM status and prevalence and incidence of LUTS, with adjustment for potential confounding variables. RESULTS: We found type 2 diabetes to be associated with prevalent LUTS (odds ratio (OR) = 1.32, 95% confidence interval (CI) 1.26, 1.38). The association was stronger among men with type 2 diabetes who were on active pharmaceutical treatment and had it for a longer duration. No association was observed between type 2 diabetes and new onset LUTS. CONCLUSIONS: Type 2 diabetes increases the risk of LUTS.