An analysis of data from the Health Professionals Follow-up Study confirms that men with diabetes mellitus are less prone to develop prostate cancer than their diabetes-free peers.

According to a report in the International Journal of Cancer, prostate cancer is 17-percent less likely to develop in men with diabetes. However, the reduced risk is not apparent until at least 1 year after the diabetes diagnosis.

Other studies have reported an inverse association between diabetes and the risk of prostate cancer. However, many of these studies have not considered the effects of lifestyle factors or time since diabetes diagnosis.

The current study featured 46,168 non-diabetic and 1613 diabetic men. During follow-up from 1986 to 2004, prostate cancer was diagnosed in 4511 men.

Men who had the disease for 1 to 6, 6 to 15, or >15 years were 18 percent, 25 percent, and 22 percent less likely to develop prostate cancer, respectively, than their nondiabetic counterparts. The inverse relationship was strongest in the pre-PSA testing era (before 1994) than afterward.

The results also showed that obese men with diabetes had a lower risk of prostate cancer than men with only one of the two conditions.

“The overall evidence for an inverse association between diabetes mellitus and prostate cancer continues to grow and studying these biological clues will continue to provide insight into the metabolic and hormonal changes behind prostatic cancer,” the authors conclude.

SOURCE: International Journal of Cancer, March 15, 2009.