SAN FRANCISCO — The presence and severity of obstructive sleep apnea was associated with worse glucose control in a study of 60 patients with type 2 diabetes.
Polysomnography and hemoglobin A1c tests showed that participants with no obstructive sleep apnea (OSA) had an average HbA1c level of 5.7%. HbA1c 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 A1c 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 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 that in nondiabetics OSA is linked with alterations in glucose metabolism and reduced insulin sensitivity. The current study is the first to show the relation between OSA severity and glycemic control in diabetes patients (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 HbA1c 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 HbA1c or insulin sensitivity. All the studies were small (ranging from 9 to 44 patients), she noted.
Studies by Dr. Tasali and associates on healthy subjects suggest that sleep interruption or deprivation similar to that which occurs with OSA may increase the risk for developing type 2 diabetes. Depriving healthy subjects of short-wave sleep for 3 nights significantly decreased insulin sensitivity and glucose tolerance and elevated cardiac sympathetic nervous activity.
“Sleep duration and quality are potentially modifiable risk factors and therefore might have important clinical implications for the prevention and treatment of diabetes and obesity,” she said.
Dr. Tasali said she had no conflicts of interest to disclose.