Diabetes mellitus is associated with elevated risk of mortality amongst patients with prostate cancer: a meta-analysis of 11 cohort studies.

PURPOSE: Diabetes mellitus is associated with a decreased risk of prostate cancer. However, previous studies examining the associations between diabetes mellitus and prostate cancer prognosis have produced mixed results. Here, we aim to summarize the effect of diabetes mellitus on prostate cancer prognosis.

METHODS: We searched the database of PubMed from inception through 31 March 2014 for articles evaluating the effect of diabetes on outcome in prostate cancer patients, and a meta-analysis was conducted.

RESULTS: A total of 11 cohort studies were included in this meta-analysis, of which seven studies were carried out to investigate whether diabetes mellitus is associated with all-cause mortality amongst those with prostate cancer, seven studies to investigate whether diabetes mellitus is associated with prostate cancer-specific mortality and two studies to investigate the relationship of diabetes mellitus and nonprostate cancer mortality. The meta-analysis results suggested that diabetes mellitus could significantly affect the incidence of all-cause mortality amongst those with prostate cancer (hazard ratio = 1.50, 95% confidence interval = 1.25-1.79). Besides, diabetes mellitus was also associated with prostate cancer-specific mortality (hazard ratio = 1.26, 95% confidence interval = 1.20-1.33) and nonprostate cancer mortality (hazard ratio = 1.83, 95% confidence interval = 1.33-2.52) separately. There was no obvious publication bias amongst the studies included.

CONCLUSION: The results of this meta-analysis reveal an association of diabetes mellitus with adverse prognosis amongst those with prostate cancer. The biological basis of the association of diabetes mellitus with prostate cancer incidence and prognosis remains unclear. Doctors could pay more attention to prostate patients with pre-existing diabetes mellitus, and more aggressive treatment regimens should be considered.