SAN FRANCISCO — The presence and severity of obstructive sleep apnea were associated with worse glucose control in a study of 60 patients with type 2 diabetes.

Polysomnography and hemoglobin (A.sub.1c) tests showed that participants with no obstructive sleep apnea (OSA) had an average (HbA.sub.1c) level of 5.7%. (HbA.sub.1c) levels averaged 7.2% in participants with mild OSA, 7.7% in those with moderate OSA, and 9.4% in those with severe OSA, Dr. Esra Tasali reported.

“These effect sizes are comparable to some medications we use to treat (A.sub.1c) levels,” she said, suggesting that “treatment of obstructive sleep apnea may improve glucose control as much as widely used pharmacologic agents.”

The linear trend for poorer glucose control with increasingly severe OSA was highly significant (P < .0001) after adjustment of the data for the effects of age, gender, race, body mass index, level of exercise, duration of diabetes, number of diabetes medications being taken, and total sleep time, she said at a meeting sponsored by the American Diabetes Association.

Previous studies have shown a high prevalence of OSA in people with type 2 diabetes and shown that in nondiabetic people OSA is associated with alterations in glucose metabolism and reduced insulin sensitivity independent of age, sex, or degree of obesity. The current study is the first to identify the rela tionship between OSA severity and glycemic control in a diabetic population (Am. J. Respir. Crit. Care Med. 2010; 181:507-13).

Overall, 77% (46 of 60) of the study cohort had OSA. Three previous studies of diabetic populations found OSA prevalences of 58%, 71%, and 86%, said Dr. Tasali of the University of Chicago.

Six trials of treating OSA in patients with type 2 diabetes using continuous positive airway pressure (CPAP) produced conflicting results, with some showing improvements in (HbA.sub.1c) levels, insulin sensitivity, or glucose levels, some showing no change, and others with split results. The only randomized clinical trial among them found no effect of CPAP therapy on (HbA.sub.1c) or insulin sensitivity. All the studies were small (ranging from 9 to 44 patients), she noted.

Dr. Tasali said that she had no conflicts of interest to disclose.

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