REM sleep-related OSA linked with diabetes

There is a statistically significant association between type 2 diabetes and obstructive sleep apnea (OSA) during REM sleep, results of a study indicate.

In comments to Reuters Health, principal investigator Dr. Kamran Mahmood said, "Type 2 diabetes is a multifactorial disorder. REM-related OSA and its metabolic effects need to be investigated in more depth, and this can provide another unique avenue for intervention and control of type 2 diabetes."

Mahmood from the University of Illinois in Chicago and colleagues evaluated a multi-ethnic sample of 1008 patients - including Caucasians (16.9 percent), African Americans (66.9 percent) and Hispanics (14.9 percent) - for OSA using polysomnography, an evaluation of brain waves and other body functions during sleep.

OSA occurs when the soft palate narrows during sleep closing off the airways causing breathing to stop for a few seconds or more. Normal breaths resume with a snort or choking sound and the sleeper temporarily wakes up. These continuous interruptions throughout the night cause drowsiness during the day. Among other effects, OSA increases the risk of heart disease.

Rapid eye movement (REM) sleep, one of the two major phases of sleep, is when dreaming occurs. As the name implies, it is characterized by rapid eye movement, but other than lung movements, no other body muscles move during this phase of sleep. It is thought to be necessary for memory consolidation.

The prevalence of type 2 diabetes was 30.1 percent in patients with OSA compared to 18.6 percent in patients without OSA, the investigators report in the June 15 issue of the Journal of Clinical Sleep Medicine.

According to the study team, patients with OSA - defined as an apnea-hypopnea index of 5 or more per hour (measurement of OSA severity) - had a significantly increased unadjusted odds ratio for type 2 diabetes but this association became non-significant in analyses controlled for BMI, age, and other variables.

Middle-aged participants with OSA had 2.8-times higher odds for type 2 diabetes compared to younger or middle-aged participants without OSA, after controlling for variables.

Additionally, the adjusted odds ratio for type 2 diabetes was 2.0 in patients with REM sleep-related OSA, defined as a REM apnea-hypopnea index of 10 or more per hour, compared to patients without OSA.

"We believe that REM-related OSA is a marker of early OSA, especially in women and patients younger than 55 years," Mahmood noted in a prepared statement. "Generally, OSA is worse in REM sleep compared to non-REM sleep because of neurologically mediated impairment of skeletal muscles of upper airway and ventilation. This may be the reason for closer association of REM-related OSA and type 2 diabetes."

SOURCE: Journal of Clinical Sleep Medicine, June 15, 2009.