Diabetes drugs tied to lower prostate cancer risk

NEW YORK (Reuters Health) - Drugs used to control diabetes may lower the risk of prostate cancer, investigators at the University of Tampere in Finland report.

"Recent studies have reported a decreased prostate cancer risk for diabetic men, although the evidence is controversial," Dr. Teemu J. Murtola and colleagues note in the American Journal of Epidemiology. "It is currently unclear whether use of antidiabetic medication affects the association between diabetes and prostate cancer."

To investigate, the investigators studied a group of men diagnosed prostate cancer and a group of "control" men without prostate cancer. The total cohort comprised 24,723 case-control pairs. The investigators also used a comprehensive prescription database to obtain information on medication use.

Oral diabetes drugs were used by 7.5 percent of men with prostate cancer and by 8.4 percent of controls. The prevalence of insulin use was 2.5 percent in the cases and 3.0 percent in the controls.

Men who had a history of taking any diabetes medication had a 16 percent lower risk of prostate cancer, Murtola's team found.

The decreased risk was comparable for all antidiabetic drugs, including metformin, sulfonylureas and insulin.

The investigators found that the overall risk, as well as the risk of advanced prostate cancer, decreased with the amount and duration of medication use.

"The potential mechanism behind decreased prostate cancer risk for diabetic men is currently unclear," Murtola's group notes. "Most likely, the changes in endogenous hormone metabolism occurring in diabetes have an important role."

SOURCE: American Journal of Epidemiology, October 15, 2008.