Sleep apnea has long been known to be associated with obesity. But a new study published in the June issue of Diabetes Care finds that the disorder is widely undiagnosed among obese individuals with type 2 diabetes - nearly 87 percent of participants reported symptoms, but were never diagnosed.
For those with untreated sleep apnea, it doesn't just mean their sleep is disrupted; existing research shows that it can also mean an increased risk of heart disease and stroke.
"The high prevalence of undiagnosed, and therefore, untreated sleep apnea among obese patients with diabetes constitutes a serious public health problem," said Gary Foster, PhD, lead author and director of the Center for Obesity Research and Education at Temple University.
The new study, called Sleep AHEAD, looked at 306 obese patients with type 2 diabetes already enrolled in the Look AHEAD trial, a 16-site study investigating the long-term health impact of an intensive lifestyle intervention in 5, 145 overweight or obese adults with type 2 diabetes.
Each participant had a sleep study (polysomnogram) that measures various breathing and brain activity during sleep. Participants also filled out a series of questions about symptoms related to sleep (snoring, sleepiness during the day), and had their weight, height, waist and neck circumferences measured.
Researchers found that 86.6 percent of participants had sleep apnea, yet reported never being diagnosed. More than 30 percent of these had between 16 and 20 episodes per hour where they would stop breathing, and 22 percent had more than 30 episodes per hour, considered severe sleep apnea. Most of these also had a larger waist circumference, which researchers found, along with higher BMI, to be significantly associated with sleep apnea.
Obesity has long been known to be associated with sleep apnea, but researchers say that these findings are alarming.
"Doctors who have obese patients with type 2 diabetes need to be aware of the possibility of sleep apnea, even if no symptoms are present, especially in cases where the patient has a high BMI or waist circumference," said Foster.
Currently, more than half of obese or overweight individuals have diabetes, the seventh leading cause of death in the United States.
Other authors on the study were Kelley Borradaile, PhD from Temple University; Mark Sanders, MD, Anne Newman, MD, David Kelley, MD, from the University of Pittsburgh; Richard Millman, MD, Rena Wing, PhD from Brown University; Garry Zammit, MD from Clinilabs; Thomas Wadden, PhD, Valerie Darcey, MS, and Samuel Kuna from the University of Pennsylvania; F. Xavier Pi SUnyer from Columbia University; and the Sleep AHEAD Research Group. Funding was provided by grants from the National Institutes of Health: National Heart, Lung, and Blood Institute and National Institute of Diabetes and Digestive and Kidney Diseases.