Could Viagra Prevent Diabetes Progression?

Erectile dysfunction drugs may improve insulin sensitivity and secretion in patients with prediabetes.

Researchers from the Vanderbilt University Medical Center conducted a randomized, double-blind, placebo-controlled study in order to test their hypothesis that sildenafil (Viagra) and other drugs for erectile dysfunction could improve adults’ insulin sensitivity and secretion without diminishing fibrinolytic function.

This hypothesis was developed after observing similar patterns in animal models, study author Nancy Brown, MD, told Pharmacy Times. In the animal models, sildenafil was demonstrated to inhibit an enzyme called phosphodiesterase 5 (PDE 5), which caused the relaxation of smooth muscles, vasodilation, and increased blood flow.

Participants in the human study were overweight and had prediabetes. Two groups of 21 participants were randomly assigned to receive either sildenafil 25 mg 3 times per day or matching placebo doses for 3 months.

The patients also underwent a hyperglycemic clamp prior to the start of the study and at the end of treatment.

The researchers found that the sildenafil patients showed significantly more sensitivity to insulin—a finding that held true even after they adjusted for baseline sensitivity index and body mass index.

“Sildenafil and related drugs could offer a potential avenue for addressing the rising number of diabetes diagnoses,” Dr. Brown said in a press release.

She also stated that weight-loss and exercise programs are a challenge for many patients with prediabetes, but current medications aimed at preventing diabetes are limited by their potential adverse effects.

The researchers also observed that sildenafil and related drugs disabled PDE 5 from breaking down a body chemical called cyclic GMP, which relaxes blood vessels and increases insulin sensitivity. Some methods for raising cyclic GMP may cause an increase in anticlotting chemicals in the body, but sildenafil did not, the researchers explained.

Dr. Brown told Pharmacy Times that although the doses of sildenafil tested in the study are not the same ones used to treat erectile dysfunction, the investigators have their eyes on another clinical trial to continue to test their hypothesis.

Their current findings were published in the Journal of Clinical Endocrinology and Metabolism.