Washington: US researchers report that disrupting sleep damages the body's ability to regulate blood sugar levels, potentially raising the risk of developing type 2 diabetes.

More than 18 million Americans have diabetes and the most common form is type 2,in which the body either becomes resistant to insulin or does not produce enough of it to regulate sugar in the bloodstream.

In a small experiment, researchers at the University of Chicago Medical Center led by Dr Esra Tasali, an assistant professor of medicine, found that disrupting the deepest sleep periods of volunteers rapidly resulted in reduction in their ability to regulate blood-sugar levels.

The findings are reported in yesterday's online edition of Proceedings of the National Academy of Sciences. The researchers studied the sleep patterns of nine volunteers, five men and four women, all of normal weight, in good health and aged 20 to 31.

Normal sleep is divided into several stages, with the so-called slow-wave sleep considered the deepest. Whenever the volunteers went into slow-wave sleep the researchers made noise - enough to disturb the sleep though not to fully awaken them.

After just three days the ability of the volunteers to regulate blood sugar was reduced by 25 per cent, the researchers reported. Earlier studies have indicated that lack of sleep can reduce the ability to regulate sugar, and this report adds evidence that poor sleep quality is also a diabetes risk.