Antidiabetic Drugs Linked to Lower Prostate Cancer Risk

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

To better define this association, the researchers examined newly diagnosed cases of prostate cancer between 1995 to 2002 from the Finnish Cancer Registry. The Population Register Center was used to randomly select matched controls, yielding a total of 24,723 case-control pairs. The authors also used a comprehensive prescription database to obtain information on medication use.

The subjects were a median of 68 years old. Oral antidiabetic drugs were used by 7.5% of men with prostate cancer and by 8.4% of controls. The prevalence of insulin use was 2.5% in the cases and 3.0% in the controls, according to the report.
An association was observed between ever using any antidiabetic medication and a decreased risk of prostate cancer (adjusted OR = 0.84). 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," Dr. Murtola's group notes. "Most likely, the changes in endogenous hormone metabolism occurring in diabetes have an important role."
Am J Epidemiol 2008;168:925-931.