Low testosterone in men may be diabetes risk factor

NEW YORK (Reuters Health) - Men with testosterone levels in the low-normal range are much more likely to have diabetes than those with higher levels, whether or not they are obese, researchers report in the journal Diabetes Care.

"Low testosterone levels are common among men with diabetes and there is growing evidence that low testosterone may be a risk factor for developing diabetes," Dr. Elizabeth Selvin from Johns Hopkins Bloomberg School of Public Health in Baltimore commented to Reuters Health.

She and her colleagues analyzed data from 1,413 men 20 years or older who participated in the Third National Health and Nutrition Examination Survey. Diabetes had been diagnosed in 101 men.

After the influence of age, race and obesity was factored in, men with the lowest levels of testosterone were four times more likely to have diabetes than men with the highest levels. Similar results were found when only the bioavailable testosterone was measured.

The association persisted even after men with low total or free testosterone levels were excluded, suggesting, the researchers say, that the association is not entirely driven by failure to produce enough testosterone.

"Obesity affects testosterone levels; testosterone levels drop in men who are overweight or obese," Selvin pointed out. Yet, "even after accounting for the effect of obesity, low testosterone levels still appear to be an important risk factor for diabetes," she said.

These data, the researchers write, support the hypothesis that male hormones directly influence sugar metabolism and the development of insulin resistance, which is seen just before diabetes occurs, independent of the effects of obesity.

Selvin added that doctors should keep in mind that "low testosterone is a common finding among men with diabetes and may lead to other clinical problems."

SOURCE: Diabetes Care, February 2007.