The U.S. Food and Drug Administration today asked manufacturers to add new warnings to labeling of gonadotropin-releasing hormone (GnRH) agonists, a class of drugs primarily used to treat men with prostate cancer.

The warnings would alert patients and their health care professionals to the potential risk of heart disease and diabetes in men treated with these medications.

In May, the FDA said that a preliminary and ongoing analysis found that patients receiving GnRH agonists were at a small increased risk for diabetes, heart attack, stroke, and sudden death. The new labels will include updates in the Warnings and Precautions section about these potential risks.

Prostate cancer is the second most common type of cancer among men in the United States, behind skin cancer, and usually occurs in older men. This year an estimated 217,730 new cases of prostate cancer will be diagnosed and about 32,050 men will die from the disease, according to the Centers for Disease Control National Center for Health Statistics and the National Cancer Institute.

GnRH agonists are drugs that suppress the production of testosterone, a hormone involved in the growth of prostate cancer. This type of treatment is called androgen deprivation therapy, or ADT. Suppressing testosterone has been shown to shrink or slow the growth of prostate cancer.

GnRH agnoists are marketed under the brand names: Eligard, Lupron, Synarel, Trelstar, Vantas, Viadur, and Zoladex. Several generic products are available.