Researchers in the US found that people they described as “short sleepers”, that is those who slept less than six hours a night were nearly five times more likely to develop abnormal levels of fasting blood sugar, a condition that can lead to type 2 diabetes.

The study was the work of lead author Dr Lisa Rafalson, a National Research Service Award fellow and research assistant professor at the University at Buffalo in New York, and the findings were presented yesterday, Wednesday 11 March, during the American Heart Association’s 49th Annual Conference on Cardiovascular Disease Epidemiology and Prevention which is taking place this week at the Westin Innsbruck Resort in Palm Harbor, Florida.

Rafalson and colleagues do not think there is a genetic reason behind their findings and hope that the study prompts more research into the links between sleep and diabetes.

Type 2 diabetes is the most common form and arises when the body can’t use the insulin it produces, and instead of being transported into cells for use as energy, the glucose stays in the blood. This causes the pancreas to produce even more insulin, which is also not used efficiently. The condition is sometimes called insulin resistant diabetes for this reason.

Type 2 diabetes mostly arises during middle age, but teenagers and young adults are now developing it at an alarming rate.

Rafalson and colleagues carried out a matched, nested case-control study involving 1,455 participants followed for six years as part of the Western New York Health Study. They wanted to find out if the amount of sleep participants were reporting at the start of the study could predict progression from normal to impaired fasting glucose over the follow up period.

They found 91 participants whose fasting glucose levels were below 100 milligrams per decilitre (mg/dL) when they enrolled in 1996-2001, had gone up to between 100 and 125 mg/dL in follow up tests in 2003-2004.

They matched each of these 91 to three controls whose glucose levels were below 100 mg/dL at enrollment and at follow up. They also matched them by gender, race/ethnicity and year of enrollment.

The results showed that participants who slept on average less than six hours a night during the working week, when followed for six years, were 4.56 times more likely to start with normal then move to impaired fasting blood glucose levels compared to counterparts who had six to eight hours.

Rafalson said:

“This study supports growing evidence of the association of inadequate sleep with adverse health issues.”

“Sleep should be assessed in the clinical setting as part of well-care visits throughout the life cycle,” she added.

Rafalson said that while some research has suggested that many genes are involved in diabetes risk, and perhaps each contributes a small effect, she and her colleagues were not aware of any that predisposed people to sleep disturbance that could explain their results, and therefore it was:

“More likely that pathways involving hormones and the nervous system are involved in the impaired-sleep/fasting glucose association.”

“Our findings will hopefully spur additional research into this very complex area of sleep and illness,” she added.

Rafalson’s co-authors were: Richard P Donahue, Michael LaMonte, Joan Dorn, Maurizio Trevisan, Saverio Stranges, and Jacek Dmochowski.

The study was sponsored by the National Institutes of Health.

Sources: American Heart Association.

Written by: Catharine Paddock, PhD