Researchers at Edinburgh University found that low levels of testosterone levels are linked to a resistance to insulin, the hormone that controls blood sugar levels. This in turn increases the risk of developing Type 2 diabetes.
It's already known that testosterone levels fall as men age, and the new findings could help explain why older men are prone to developing diabetes, the researchers said.
"We know that men with low testosterone levels are more likely to become obese, and as a develop diabetes," said study author Dr Kerry McInnes, from the University of Edinburgh's Endocrinology Unit.
"This study shows that low testosterone is a risk factor for diabetes no matter how much a person weighs.
As men age their testosterone levels lower. This, along with increasing obesity, will increase the incidence of diabetes," Dr McInnes was quoted as saying by LiveScience.
Testosterone, which is present throughout the body, acts on fat cells through molecules called androgen receptors that enable the testosterone to activate genes linked to obesity and diabetes.
The study, funded by Diabetes UK and carried out on mice, showed that mice, which didn't have androgen receptors in fat tissue for testosterone to attach to, were more likely to show signs of insulin resistance than other mice.
Mice without androgen receptors in fat tissue also became fatter than other mice and developed full insulin resistance when both types were fed a high-fat diet.
Scientists believe that a protein called RBP4 plays a key role in regulating insulin resistance when testosterone is impaired. The study showed that levels of RBP4 were higher in mice in which the role of testosterone was impaired.
Mice are considered good analogues to humans, but more research is needed to confirm the work, the researchers said.
The findings could lead to the development of new drugs that can regulate production of RBP4 and reduce the risk of diabetes in men with low testosterone levels, they added.