WEDNESDAY, Nov. 18, 2015 (HealthDay News) -- The impotence drug Viagra may help ward off type 2 diabetes in people already at risk for the illness, a small new trial suggests.
The study, funded by the U.S. National Institutes of Health, found that Viagra (sildenafil) improved "insulin sensitivity" in overweight, pre-diabetic people. Insulin sensitivity involves the body's ability to efficiently use the hormone.
The erectile dysfunction drug was also tied to a lowering of levels of a marker associated with a raised risk of heart and kidney disease, the researchers reported Nov. 18 in the Journal of Clinical Endocrinology & Metabolism.
However, the trial was small -- just 42 patients -- and "further studies will be needed to determine whether long-term treatment with drugs like sildenafil can prevent the onset of diabetes in high-risk patients," study lead author Dr. Nancy Brown said in a journal news release.
Brown and her colleagues at Vanderbilt University School of Medicine in Nashville tracked outcomes for 42 overweight men and women with pre-diabetes.
All of the patients were randomly assigned to take Viagra (25 milligrams, three times per day) or an inactive placebo for three months.
By the end of that time, those in the Viagra group were more sensitive to insulin and also had lower levels of albumin in their urine (a marker of heart and kidney disease risk) than those in the placebo group, the researchers found.
Without treatment, as many as 30 percent of people with pre-diabetes go on to develop type 2 diabetes within five years, Brown's team pointed out.
"Because existing drug therapies to prevent type 2 diabetes can have negative effects on the heart or be of limited use in patients with kidney disease, strategies to prevent diabetes without adversely affecting the risk of kidney and heart disease could have a large impact on public health," she said in the news release.
According to the study authors, Viagra works by inhibiting an enzyme that breaks down a natural blood vessel-relaxing chemical called cGMP. Other drugs that boost levels of the chemical are under development.
Just how might Viagra and drugs like it keep diabetes at bay? One expert offered some ideas.
Drugs in this class, "such as Cialis, Levitra and Viagra, have long been known to have beneficial effects not only on erectile function, but also on the function of the endothelium, the inner lining of blood vessels," explained Dr. Ronald Tamler, medical director at the Mount Sinai Clinical Diabetes Institute in New York City.
And he added that "subtle effects on glucose [blood sugar] metabolism and insulin resistance have been previously described in animal models and very small-scale human studies."
Dr. Rifka Schulman is director of inpatient diabetes at Long Island Jewish Medical Center in New Hyde Park, N.Y. She agreed that, while the finding is interesting, "further research would be needed with larger studies and over longer periods of time to determine if sildenafil would be an appropriate drug for diabetes prevention."
The American Academy of Family Physicians has more about pre-diabetes.
SOURCES: Ronald Tamler, M.D., medical director, Mount Sinai Clinical Diabetes Institute, Mount Sinai Health System, New York City; Rifka C. Schulman, M.D., director, inpatient diabetes, Long Island Jewish Medical Center, New Hyde Park, N.Y.; Journal of Clinical Endocrinology & Metabolism, news release, Nov. 18, 2015
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