Men with impotence are more likely than others to have undiagnosed diabetes and should be screened for the disease with a blood sugar test, according to UK researchers.

“If you have erectile dysfunction, one should suspect diabetes as the underlying cause,’’ study co-author Dr. Krishnamurthy Sairam, of Kent & Sussex Hospital, told Reuters Health. “Fasting blood glucose testing should be the standard test to screen for diabetes in men presenting with erectile dysfunction.’‘

The researchers, led by Dr. Tom McNicholas of Lister Hospital in Stevenage, studied 129 men who had visited the hospital’s urology department because they were unable to sustain an erection.

Diabetes and other chronic diseases that affect the blood vessels, nerves and smooth muscle commonly underlie impotence. So all men in the study were tested for diabetes using both a urinary dipstick testing for glycosuria-excess sugar in the urine-as well as a fasting blood glucose test.

Overall, 22 of the 129 men had been previously diagnosed with diabetes. Of the remaining 107, the blood test revealed that nearly 5% unknowingly had the disease, according to findings published in a recent issue of the British Journal of Urology.

The blood glucose test also found that an additional 12% of these men had abnormal glucose levels that could lead to diabetes if not managed with proper diet and exercise.

However, the investigators found that the urinary dipstick test failed to diagnose four out of five men with diabetes. ‘‘Urine testing (had) a sensitivity of just 20%-extremely poor performance for a diagnostic test,’’ Sairam said. “Urine glucose measurement is thus a very insensitive and unreliable test for diabetes.’‘

Because men with erectile dysfunction are around four times more likely than the average male to have unrecognized diabetes, the researchers conclude that doctors should screen all impotent males for diabetes.

“The first presentation of a man with erectile dysfunction presents an ideal opportunity to do the fasting blood glucose test and rule out diabetes,’’ Sairam said. “Otherwise, diabetes may remain undiagnosed for several more years.’‘