Researchers at the Yale University School of Medicine have found that patients with obstructive sleep apnea are at increased risk for developing of type II diabetes, independent of other risk factors. The findings are being presented at the American Thoracic Society 2007 International Conference, on Monday, May 21.
The study looked at 593 patients at the VA Connecticut Health Care System referred for evaluation of sleep-disordered breathing. Each patient spent a night in a sleep laboratory to undergo a sleep study, called polysomnography.
The researchers followed the subjects for up to six years and found that patients diagnosed with sleep apnea had more than two-and-half times the risk of developing diabetes compared with those without the nighttime breathing disorder. The patients were then divided into groups based on the severity of their sleep apnea, and the more severe a patient's sleep apnea, the greater the risk of developing diabetes.
In obstructive sleep apnea, the upper airway narrows, or collapses, during sleep. Periods of apnea end with a brief partial arousal that may disrupt sleep up to hundreds of times a night. Obesity is a major risk factor for sleep apnea. Emerging evidence also exists that sleep apnea is associated with hypertension, stroke and heart disease.
The most effective treatment for sleep apnea is a treatment called continuous positive airway pressure (CPAP), which delivers air through a mask while the patient sleeps, keeping the airway open. It is successful in treating sleep apnea and improving daytime drowsiness, resulting in an improved quality of life and even reduction in risk for traffic accidents. It has yet to be determined whether treatment for sleep apnea with CPAP can actually improve conditions such as diabetes.
"Our next step will be to determine whether the treatment of sleep apnea can improve an individual's diabetic parameters and consequently the negative health effects of diabetes." says researcher Nader Botros, M.D., of Yale University.
Dr. Botros said that although it is not known exactly what the link is between sleep apnea and diabetes, it is thought that sleep apnea activates the body's fight-or-flight response. This triggers a cascade of events, including the production of high levels of the hormone cortisol that ultimately leads to insulin resistance and glucose intolerance, pre-diabetic conditions that, if left untreated, can lead to the development of diabetes. Low oxygen levels also appear to play an important role.
"The impact of diabetes on public health is great," Dr. Botros says. "Diet and exercise, along with a medication regimen, are the mainstays of treatment, but unfortunately diabetes remains a major public health challenge. New approaches are needed to better understand the risk factors for diabetes in order to develop additional preventive strategies. Understanding the link between sleep-disordered breathing and diabetes may represent one such approach."