Sleep Apnea-Diabetes Link Confirmed in Large Study

Larry Hand

June 09, 2014

Severe obstructive sleep apnea (OSA) may increase a person's risk of developing diabetes by 30% or more, according to an article published online June 6 in the American Journal of Respiratory and Critical Care Medicine.

Now that that link has been confirmed in a large trial with a long follow-up period, clinicians may be able to intervene and take diabetes prevention measures for patients with OSA who have not yet developed the disease, researchers write.

Tetyana Kendzerska, MD, PhD, from the Institute of Health Policy, Management, and Evaluation, University of Toronto, Ontario, Canada, and colleagues analyzed provincial health data on 8678 adults without diabetes who underwent a diagnostic sleep study for suspected OSA between 1994 and 2010. The researchers followed the patients through May 2011. The study population had a median age of 48 years, and 62% of patients were men.

Of the 8678 patients who underwent the sleep study, 1017 (11.7%) developed diabetes during a median of 67 months of follow-up, which translates to a cumulative incidence of 9.1% at 5 years (95% confidence interval [CI], 8.4% - 9.8%). Incidence came to 7.5% (95% CI, 6.3%-8.6%) for patients with mild OSA, 9.9% (95% CI, 8.3%-11.4%) for moderate OSA, and 14.9% (95% CI, 13.2%-16.6%) for severe OSA.

The researchers analyzed all OSA-related variables, including total sleep time, amount of rapid eye movement sleep, total awakenings, oxygen saturation, and heart rate. They also adjusted for age, sex, body mass index, waist circumference, and self-reported tobacco and alcohol use.

They developed an apnea-hypoxia index on the basis of the number of complete apneas and partial apneas (hypopneas). The apnea-hypoxia index ranged from less than 5 for no OSA diagnosis, to between 5 and 14.9 for mild OSA, to 15 to 30 for moderate OSA, and to more than 30 for severe OSA.

In fully adjusted Cox regression modeling, patients with severe OSA had a 30% or higher increased hazard of developing diabetes than patients without OSA (hazard ratio [HR], 1.31; 95% CI, 1.07 - 1.61, severe). Mild and moderate OSA patients carried a 23% higher risk (HR, 1.23; 95% CI, 1.00 - 1.50 and 1.00 - 1.51, respectively).

Other OSA-related diabetes incidence predictors included heart rate during sleep, oxygen desaturation, lack of sleep, daytime sleepiness, and greater neck circumference.

Possible Mechanisms

The findings coincide with pathophysiological mechanisms thought to lead to diabetes, including "oxidative stress caused by intermittent hypoxemia, sleep deprivation or fragmentation, and sympathetic activation," the researchers write. They also point out that greater neck circumference has been linked to insulin resistance.

Limitations of the study include missing data on some potential confounders, such as race and family history of diabetes and the inability to categorize diabetes as type 1 or type 2. "However, we expect the vast majority of events to be Type 2 because of the age of our cohort," the researchers write.

Although previous research has linked OSA to diabetes incidence, studies have been small and have had shorter follow-up periods, the researchers write.

"Our study, with a larger sample size and a median follow-up of 67 months, was able to address some of the limitations of earlier studies on the connection between OSA and diabetes," Dr. Kendzerska said in a news release.

"[W]e were able to demonstrate a significant association between OSA severity and the risk of developing diabetes," he added.

"The OSA-related predictors of increased diabetes risk that we found in our study may allow for early preventative interventions in these patients."

This project was supported by the ResMed research foundation and the Institute for Clinical Evaluative Sciences, which is funded by an annual grant from the Ontario Ministry of Health and Long-Term Care. Dr. Kendzerska is supported by Canadian Institutes of Health Research doctoral research award. One coauthor is supported by the F.M. Hill Chair in Academic Women’s Medicine. Another coauthor is supported by a fellowship from the Physicians’ Services Incorporated Foundation. The other authors have disclosed no relevant financial relationships.

Am J Respi Crit Care Med. Published online June 6, 2014. Abstract

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