The effects of weight loss on obstructive sleep apnea in obese patients with type 2 diabetes

Sleep apnea is a common disorder in which an individual may have one or more pauses in breathing or shallow breaths while they sleep. It is estimated that more than 12 million Americans have sleep apnea and more than half of those with this condition are overweight. If left untreated, sleep apnea can increase an individual’s risk for high blood pressure, stroke, heart attack, and heart failure, as well as increase his/her risk of having work-related or driving accidents.

What was the study?

The research, “A randomized study on the effect of weight loss on obstructive sleep apnea among obese patients with type 2 diabetes,” was funded by the National Heart, Lung, and Blood Institute and published in Archives of Internal Medicine, September 2009.

• Participants were 264 individuals enrolled in the Sleep AHEAD (Action for Health in Diabetes) study. They were 59% female, averaged 61.2 years of age, had type 2 diabetes and obstructive sleep apnea, and had an average body mass index of 36.7 kg/m².
• The apnea-hypopnea index (AHI) is a measure of obstructive sleep apnea severity and was defined as the sum of the number of apneas and hypopneas per hour. AHI was assessed by unattended overnight polysomnogram (PSG) in the participants’ homes.
• Individuals were randomized to a behavioral weight loss program (intensive lifestyle intervention – referred to as lifestyle intervention) or three group sessions of diabetes support and education (referred to as diabetes education).
• The lifestyle intervention included a group behavioral weight loss program developed for obese patients with type 2 diabetes.
  • Prescribed energy intake was 1200-1500 kcal/day for individuals who weighed less than 113.6 kg and 1500-1800 kcal/day for those who weighed more, with 30% or less calories from fat.
  • Participants were prescribed portion controlled diets that included liquid meal replacements, frozen food entrees, and snack bars for the first 4 months, with reduced use over the remaining year intervention.
  • The program included 175 minutes/week of moderate-intensity activity, such as brisk walking.
• The diabetes education program consisted of three group sessions over the 1-year period that focused on diet, physical activity, and social support as related to diabetes management.

What did the study find?

• At the start of the study over 95% of the participants had clinically significant obstructive sleep apnea, with an average AHI of 10 events/hour.
• After 1 year, lifestyle intervention group participants had an average weight loss of 10.8 kg compared to 0.6 kg in the diabetes education group.
• The lifestyle intervention group participants exhibited a significant improvement in obstructive sleep apnea, with an average decrease in AHI of 9.7 events/hour relative to the diabetes education group. More than twice as many in the lifestyle intervention group as compared to the diabetes education group had an improvement in their obstructive sleep apnea category (improving from severe to moderate, moderate to mild, or mild to none).
• Average obstructive sleep apnea severity increased among the diabetes education participants, despite their weight remaining stable. Apnea severity among these participants increased by 4 events per hour over 1 year, which edged their obstructive sleep apnea towards the severe category.
• At the 1-year follow up, only 5% of study participants reported receiving continuous positive airway pressure (CPAP) therapy, which is the most common treatment for moderate to severe sleep apnea in adults.

What are the take-home messages?

• Sleep apnea in obese individuals with type 2 diabetes is extremely common, but may often go undiagnosed and untreated.
• A lifestyle intervention program that results in marked weight loss can significantly improve obstructive sleep apnea. This improvement may help lower an individual’s risk for high blood pressure, heart disease, and stroke, independent of other risk factors.
• Extrapolating from findings in other studies, decreasing apnea severity may have additional benefits including improved daytime vigilance, cognitive performance, and mood.
• Individuals who successfully lose weight and decrease the severity of their obstructive sleep apnea may still need treatment for this potentially serious condition.
• The high prevalence of untreated obstructive sleep apnea in adults suggests that health care providers may want to consider the possibility of obstructive sleep apnea among obese type 2 diabetic patients and whether there may be some benefit to evaluation and treatment of individuals at risk.

Where can I learn more?

• A randomized study on the effect of weight loss on obstructive sleep apnea among obese patients with type 2 diabetes. Foster, G.D., et al., Archives of Internal Medicine, 169(17):1619-1626, 2009.
• Obstructive sleep apnea among obese patients with type 2 diabetes. Foster, G.D. et al., Diabetes Care, 32(6):1017-9, 2009, DOI: 10.2337/dc08-1776.
• Recovery Act-funded scientist Susan Redline, M.D., M.P.H. discusses sleep apnea
• NHLBI Diseases and Conditions Index: Sleep Apnea
• 2003 National Sleep Disorders Research Plan
• Your Guide to Healthy Sleep
• Look AHEAD Participant Web site
• Sleep Apnea Tied to Increased Risk of Stroke. Even Mild Sleep Apnea Puts Men in Danger. (Press release)

Additional information on the study:

• The Sleep AHEAD study is an ancillary investigation of the Look AHEAD study, a 16-center randomized, controlled clinical trial investigating the long-term health impact of an intensive lifestyle intervention. Participants were recruited from four Look AHEAD sties: University of Pennsylvania, Philadelphia; University of Pittsburgh, Pa; Columbia University, New York, N.Y.; and Brown University, Providence, R. I.