GnRH therapy boosts diabetes risk in men with prostate cancer

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Gonadotropin-releasing hormone (GnRH) agonist treatment for prostate cancer appears to increase the chances of diabetes development, according to Boston-based researchers.

As lead investigator Dr. Matthew R. Smith told Reuters Health, "GnRH agonists significantly decrease insulin sensitivity in nondiabetic men with prostate cancer. This observation suggests that hormone therapy increases risk for (type 2) diabetes, a condition defined by insulin resistance."

In the April issue of the Journal of Clinical Endocrinology and Metabolism, Dr. Smith and colleagues at Massachusetts General Hospital note that they prospectively followed 26 men with locally advanced or recurrent prostate cancer who underwent treatment with leuprolide depot and bicalutamide.

At 12 weeks, the proportion of fat body mass increased by 4.3%. Insulin sensitivity index fell 12.9% and insulin sensitivity calculated by homeostatic model assessment decreased by 12.8%. Fasting plasma insulin levels increased by 25.9% and there was a significant increase in mean glycosylated hemoglobin.

Moreover, continued Dr. Smith, "because insulin resistance is also linked to cardiovascular disease, our observation suggests that GnRH agonists may increase risk of cardiovascular disease."

"Based on this previously unrecognized potential harm," he concluded, "we recommend caution in using GnRH agonists in settings where impact on overall survival is unknown, and screening for diabetes during therapy" in men who require such treatment.