Linking Sleep Disorders and Diabetes

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Sleep-disordered breathing and impaired glucose metabolism in normal-weight and overweight/obese individuals, by Sinziana Seicean and colleagues. Diabetes Care 31:1001–1006, 2008

What is the problem and what is known about it so far?

Sleep-disordered breathing (SDB) is a chronic illness that causes people to partially or completely stop breathing for short periods of time during sleep. It may affect up to 17 percent of middle-aged people and 20 percent of older adults in the U.S. The symptoms of SBD have been linked to poor metabolic function, including problems processing glucose. Evidence is building that links SDB with type 2 diabetes, but the role of overweight in this link is not yet known. Also, the link between SDB and signs of pre-diabetes (glucose levels higher than normal but not high enough to diagnose diabetes) is unclear.

Why did researchers do this particular study?

The researchers wanted to learn about the relationship between SDB and pre-diabetes in people of different body weights.

Who was studied?

Subjects included 2,588 people who were 52-96 years old and did not have known diabetes.

How was the study done?

Researchers analyzed results of two standard measurements of glucose metabolism (fasting glucose and glucose tolerance) and compared those of participants with and without SDB after accounting for numerous factors including age, sex, race, BMI, and waist circumference.

What did the researchers find?

People with SDB, whether they were normal-weight or overweight, had significantly higher rates of impaired fasting glucose, impaired glucose tolerance, both impairments together (a sign of advanced pre-diabetes and greater risk for rapid progression to diabetes, heart disease, and premature death), and unknown diabetes.

What were the limitations of the study?

The study included fewer normal-weight subjects than overweight subjects with SDB, so detailed analysis of the differences between the two groups was not possible. However, the results for both groups were still consistent enough to show a link between SDB and pre-diabetes regardless of body weight. There were also problems involving blood glucose testing and sleep studies not occurring at the same time. However, because both conditions are chronic with fairly stable test results over time, this should not have greatly biased the results. Finally, because the subjects were mostly older and Caucasian, the results may not fully apply to younger groups or ethnic minorities.

What are the implications of the study?

People with SDB are at special risk for diabetes and heart disease, regardless of their weight. This link may be related to the physical stress that occurs overnight in individuals who suffer from SDB. More research is needed to find strategies to reduce this risk. Meanwhile, it is important to identify patients with SDB and to monitor their glucose metabolism over time.

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