People who sleep less than six hours nightly risk developing diabetes

To the many problems associated with lack of sleep -- moodiness, memory problems, difficulty concentrating -- add the risk of developing diabetes.

A study from the University at Buffalo shows that people who sleep less than six hours a night during the work-week are 4.5 times more likely to have elevated levels of blood sugar than those who slumber 6-8 hours.

The findings were presented yesterday at the American Heart Association's 49th annual Conference on Cardiovascular Disease Epidemiology and Prevention.

"Impaired fasting glucose -- a reading higher than 100 -- is known as pre-diabetes, which is a precursor to type 2 diabetes," said Lisa Rafalson, Ph.D., a National Research Service Award (NRSA) Fellow in the UB Department of Family Medicine and first author on the study.

"In fact, about 25 percent of people who have impaired fasting glucose will at some point develop type 2 diabetes, which is associated with many complications, including heart disease and premature death." Rafalson also is a research assistant professor is UB's Department of Social and Preventive Medicine.

Rafalson's findings were based on data from an average six-year follow-up of participants who initially took part in the Western New York Health Study, conducted from 1996-2001. The 91 persons with normal fasting glucose levels at baseline who developed pre-diabetes by their follow-up exam were matched to persons from the study who had maintained normal glucose levels who served as controls.

Participants were placed into three groups based on the average daily amount of sleep they reported receiving from Sunday through Thursday: short-sleepers -- those who reported less than 6 hours of sleep nightly; long-sleepers, who reported sleeping more than eight hours nightly; and a reference group who slept 6-8 hours a night.

Results showed that "short-sleepers" had a significantly increased risk of progressing from normal glucose levels to pre-diabetes, compared to those who slept 6-8 hours nightly. Sleeping an average of more than 8 hours a night had no significant effect on glucose levels, results showed.

"This study supports growing evidence of the association of inadequate sleep with adverse health issues," said Rafalson. She suggested that during annual "well" visits, physicians should discuss sleep habits with their patients, along with diet and exercise and other lifestyle issues that are important to long-term health.

"Genetic susceptibility is always a possible explanation for this finding," Rafalson noted, "but it is more likely that pathways involving hormones and the nervous system are involved in the impaired-sleep/fasting glucose association.

"We hope our findings will generate more research into this complex relationship between sleep and illness," she said.

Additional authors on the study are Richard P. Donahue, Ph.D., M.P.H.; Michael LaMonte, Ph.D., M.P.H.; Joan Dorn, Ph.D.; Maurizio Trevisan, M.D., M.S.; Saverio Stranges, M.D., Ph.D.; and Jacek Dmochowski, Ph.D. All authors are current or former members of the Department of Social and Preventive Medicine, UB School of Public Health and Health Professions.

Trevisan now heads the University of Nevada Health Sciences System; Stranges is affiliated with the Clinical Sciences Research Institute, Warwick Medical School, Coventry, UK, and Dmochowski is affiliated with the University of North Carolina, Charlotte.

The study was funded by the National Institutes of Health.

The University at Buffalo is a premier research-intensive public university, a flagship institution in the State University of New York system and its largest and most comprehensive campus. UB's more than 28,000 students pursue their academic interests through more than 300 undergraduate, graduate and professional degree programs. Founded in 1846, the University at Buffalo is a member of the Association of American Universities.