Weight loss should result in significant and clinically relevant improvements in obstructive sleep apnea (OSA) among obese patients with type 2 diabetes, according to the results of a multicenter randomized study published in the September 28 issue of the Archives of Internal Medicine.
"The belief that weight loss improves...OSA has limited empirical support," write Gary D. Foster, PhD, from the Center for Obesity Research and Education, Temple University in Philadelphia, Pennsylvania, and colleagues from the Sleep AHEAD Research Group of the Look AHEAD Research Group. "The purpose of this 4-center study was to assess the effects of weight loss on OSA over a 1-year period."
The study sample consisted of 264 participants with type 2 diabetes who were randomly assigned to either an intensive lifestyle intervention (behavioral weight loss program developed specifically for obese patients with type 2 diabetes) or to a diabetes support and education group (3 group sessions discussing effective diabetes management). Mean age was 61.2 ± 6.5 years, mean weight was 102.4 ± 18.3 kg, mean body mass index (calculated as weight in kilograms divided by height in meters squared) was 36.7 ± 5.7 kg/m2, and mean apnea-hypopnea index (AHI) was 23.2 ± 16.5 events per hour.
Compared with participants in the support and education group, participants in the intensive lifestyle group lost more weight at 1 year (10.8 kg vs 0.6 kg; P < .001) and had a relative adjusted decrease in AHI of 9.7 ± 2.0 events per hour (P < .001). Total remission of OSA at 1 year occurred in more than 3 times as many participants in the intensive lifestyle group vs the support and education group, and the prevalence of severe OSA in the intensive lifestyle group was half that in the support and education group. The factors most predictive of changes in AHI at 1 year were initial AHI and weight loss (P < .01), with the greatest reductions in AHI occurring in participants with weight loss of at least 10 kg.
"Physicians and their patients can expect that weight loss will result in significant and clinically relevant improvements in OSA among obese patients with type 2 diabetes," the study authors write. "The greatest benefit was observed in men, in participants with more severe OSA at baseline, and in participants who lost the most weight."
Limitations of this study include lack of generalizability to younger patients, to patients without type 2 diabetes, or to patients with milder degrees of OSA. In addition, future research should address the mechanical, metabolic, and hormonal mechanisms underlying these improvements in OSA.
"The significant increase in AHI over 1 year in participants who were weight stable suggests that OSA is a rapidly progressing syndrome that will worsen without treatment in middle-aged obese adults with type 2 diabetes," the study authors conclude.
The National Institutes of Health (NIH) National Heart, Lung, and Blood Institute supported Sleep AHEAD. The NIH National Institute of Diabetes and Digestive and Kidney Diseases supported Look AHEAD. One of the study authors (Dr. Sanders) has disclosed various financial relationships with Philips-Respironics, Cephalon, and Sanofi-Aventis.
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