Scientists from the University of Chicago suggest that not getting quality sleep may increase a person's risk of developing diabetes.

The researchers say a disturbed night's sleep may lead to high blood sugar levels, weight gain and, eventually, even type 2 diabetes because the body becomes unable to recognise normal insulin signals.

It is already known that the deepest form of sleep, known as slow-wave sleep, affects a person's metabolism and previous studies have also shown an association with diabetes and a lack of sleep.

The research team led by Dr. Esra Tasali, who wanted to test the impact of sleep quality on blood glucose control, conducted a study involving nine healthy and slim men and women.

The volunteers were first monitored for two consecutive nights in order to establish what their normal sleep patterns were, then on the following three nights, the research team woke them with a loud noise when they drifted into deep sleep.

The team discovered after injecting the volunteers with glucose and measuring their daytime blood sugar levels and insulin response, that eight of them had developed insulin resistance even though the overall amount of sleep they had remained unchanged.

Dr. Tasali says strategies should be considered to improve sleep duration and quality as a potential intervention to prevent or delay the development of type 2 diabetes.

Tasali says the alarming rise in the prevalence of type 2 diabetes associated with an ageing population and increased obesity, indicates the importance of understanding the factors that promote its development.

Dr. Tasali says restricting sleep duration in healthy young adults results in decreased glucose tolerance and the current data indicates that not only reduced sleep duration but also reduced sleep quality may play a role in diabetes risk.

Dr. Tasali also says as chronic shallow sleep and diabetes are typical factors associated with ageing, more research is needed to find out if age-related changes in sleep quality contribute to such metabolic changes.

The study appears in the Proceedings of the National Academy of Sciences.

Dr. Winkelman says although the study does not show that RLS causes cardiovascular and cerebrovascular disease, a number of potential mechanics for such a process exist.

He says most people with RLS have as many as 200 to 300 periodic leg movements each night of sleep and these leg movements are associated with substantial acute increases in both blood pressure and heart rate, which may, over the long term, produce cardiovascular or cerebrovascular disease.

The researchers also say sleep deprivation may also play a role in the association with heart disease.

Winkelman says there are limitations to the study, including that the diagnosis of RLS was self-reported by questionnaire rather than by clinical interview.

The research, which confirms smaller studies, was supported by the National Heart, Lung and Blood Institute and is published in the January 1, 2008, issue of Neurology, the medical journal of the American Academy of Neurology.