LONDON: Successive nights of disturbed sleep appear to put people at greater risk of developing type 2 diabetes, according to research in which scientists interfered with volunteers’ sleep patterns.

The research is the first to show that disturbed sleep can affect the production of insulin, and consequently a person’s ability to metabolise glucose. It could have huge implications for understanding and tackling the diabetes epidemic that is predicted to grip western countries due to increasingly obese populations.

Between 85 per cent and 95 per cent of diabetes cases are type 2, which typically develops later in life and is linked to obesity.

Eve Van Cauter, a professor at the University of Chicago, and colleagues studied five healthy men and four healthy women aged between 20 and 31. The volunteers received two consecutive nights of undisturbed sleep and three nights during which they were prevented from entering the most restorative stages three and four of slow-wave sleep — a time when you do not dream.

The scientists achieved this by monitoring the volunteers’ brain waves and jolting them out of slow-wave sleep with recorded sounds that were not loud enough to actually interrupt sleep. On average, the volunteers needed 250 to 300 interventions a night. After allowing the volunteers either normal or impaired sleep, the researchers injected a standard amount of glucose into their bloodstreams and monitored how well they dealt with it.

The team reported on Tuesday in Proceedings of the National Academy of Sciences that after three nights of disturbed sleep the volunteers were significantly glucose-intolerant: they had, on average, 23 per cent more glucose in their blood. That is a decrease in insulin sensitivity comparable to that caused by gaining 9-13kg in weight. Also, those with low baseline levels of slow-wave sleep had the lowest levels after having their sleep patterns disrupted.

“A profound decrease in slow-wave sleep had an immediate and significant adverse effect on insulin sensitivity and glucose tolerance,” said team member Esra Tasali

The results suggest obesity and a lack of quality sleep may interact to cause type 2 diabetes.—Dawn/Guardian News Service