Sleep Apnea and Diabetes

Researchers in Chicago think so. They treated sleep apnea in a group of 24 people who also had type 2 diabetes, and found significant improvements in glucose and A1C levels. The Chicago team developed the study because evidence suggests a link between the two conditions.

Sleep apnea is a disorder in which the throat muscles relax during sleep, obstructing the airway and causing brief but frequent breathing interruptions. Obesity-a common problem for people with type 2-is a major risk factor for developing this sleep disorder. Also, previous research has shown that sleep apnea is independently linked to glucose intolerance and insulin resistance-the primary characteristics of type 2.

This means that people with type 2-whether they are obese or not-may be at risk for developing sleep apnea. And anyone with both type 2 and sleep apnea is at risk for increased glucose intolerance.

Each person in the study was given a continuous positive airway pressure (CPAP) machine to use when sleeping (an average of 5 to 6 hours per night). The CPAP blows a constant stream of air through a mouth and nose mask to keep the user's airway open and breathing uninterrupted. The machines were equipped with microchips that recorded when and for how long the participants used them.

After the CPAP test period-an average of 83 days-researchers found that glucose values measured 1 hour after a meal were significantly reduced from a range of approximately 191-199 mg/dl before the study to approximately 130-137 mg/dl after. The results were most significant for participants who kept the CPAP on for at least 4 hours or more per night. Group A1C levels went from 8.3 percent at the beginning of the study to 7.9 percent.

The subgroup of participants whose beginning A1C levels were over 7.0 percent showed even more improvement, with an average of 9.2 percent before treatment to 8.6 percent after. A1C improvement was also closely tied to the number of days the CPAP was used for 4 hours or more.

The study's authors believe that these results indicated that treating sleep apnea could possibly delay the onset of diabetes in individuals with pre-diabetes and reduced cardiovascular risk in people with type 2 diabetes. This study was published in the Archives of Internal Medicine in February 2005.