Diabetes is associated with a reduced risk of prostate cancer, but only several years after diagnosis of diabetes.
A recent study asked participants to complete a questionnaire including information on diabetes at enrollment in 1992 and at follow-up in 1997 and 1999. The study authors documented 5,318 cases of incident prostate cancer through August 31, 2001, among 72,670 men.
The results of the study showed that diabetes was associated with a lower incidence of prostate cancer. However, this incidence varied significantly by the time of diagnosis. The risk of prostate cancer was slightly increased during the first three years after diagnosis of diabetes. It was reduced among men diagnosed four or more years before.
—American Journal of Epidemiology, January 15, 2005