Diabetes associated with lower incidence of prostate Ca

Diabetes appears to be associated with a reduced risk of prostate cancer, according to an article in the American Journal of Epidemiology (2005; 161:147-52).

"Study results are consistent with the hypothesis that diabetes is associated with reduced risk of prostate cancer but only several years after diagnosis of diabetes," wrote the authors, led by Carmen Rodriguez, MD, of the American Cancer Society.

Researchers compared the timing of diabetes diagnosis and the risk of prostate cancer among men in the Cancer Prevention Study II Nutrition Cohort. Participants answered questionnaires on diabetes at enrollment in 1992 and then follow-up questionnaires in 1997 and 1999. Researchers also reviewed historical information on diabetes from a 1982 study. Through August 2001, the authors reviewed 5,318 cases of incident prostate cancer.

Cox proportional hazards models showed that diabetes was associated with a lower incidence of prostate cancer (rate ratio=0.67, 95% confidence interval: 0.60, 0.75).

Time since diagnosis of diabetes influenced prostate cancer risk. Risk of prostate cancer slightly increased during the first 3 years after diagnosis of diabetes (RR=1.23, 95% CI: 0.92, 1.65) but decreased among men diagnosed 4 or more years before (RR=0.63, 95% CI: 0.56, 0.71), according to the authors.