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5-12-20

Poor sleep also linked with higher blood sugar levels in African Americans

• African American men and women who had severe sleep apnea or other disrupted sleep patterns had higher blood sugar levels than those who slept normally.
• More research is needed to see whether treating sleep apnea and supporting better sleep habits can reduce the risk of diabetes.

African American men and women are up to two times more likely to develop diabetes over their lifetimes than white Americans. Diabetes occurs when your blood glucose (also called blood sugar) is too high. Over time, high levels of blood glucose can cause heart disease, nerve damage, eye problems, and kidney disease.

Previous studies in white and Asian populations have linked disturbances in sleep to increased blood glucose levels. These disturbances may be caused by sleep apnea, a condition where breathing stops or gets very shallow for periods during the sleep cycle. Sleep apnea reduces the amount of oxygen that reaches the organs of the body, potentially leading to many health problems.

To see if links between disrupted sleep and high blood glucose levels also exist in African Americans, researchers led by Dr. Yuichiro Yano from Duke University looked at data collected between 2012 and 2016 by the Jackson Heart Study. This community-based study looked at risk factors for heart disease among African American men and women living in the Jackson, Mississippi metropolitan area.

The analysis included about 800 participants who underwent home sleep apnea testing. They also wore a wrist actigraph (a device that measures wakefulness and sleep) for a week, and kept a sleep diary. This information was used to calculate how long people slept, how often they woke up during the night, and variability in these sleep patterns. Measurements of blood glucose were taken in the clinic.

The participants were mostly women, and about 25 percent had diabetes. Around a third were found to have sleep apnea, most of whom were not receiving treatment for the condition. The study was funded in part by NIH's National Heart, Lung, and Blood Institute (NHLBI) and National Institute for Minority Health and Health Disparities (NIMHD). Results were published on April 28 in the Journal of the American Heart Association.

Both sleep apnea and fragmented sleep patterns recorded during the study were associated with higher blood glucose levels. These associations remained after the researchers adjusted for other factors including age, sex, weight, smoking and alcohol use, and history of diabetes and heart disease.

People with the most severe sleep apnea had 14 percent higher fasting blood glucose levels than those without sleep apnea. In people who already had diabetes, greater disturbances in sleep were associated with lower sensitivity to insulin, the hormone that signals cells to take up sugar from the blood.

"Our results reaffirm the need to improve the screening and diagnosis of sleep apnea, both in African Americans and other groups," Yano says. Past studies have found that many people with sleep apnea don't know they have the condition.

Treatments for sleep apnea include lifestyle changes and use of a continuous positive air pressure (CPAP) machine. More research is needed to determine if treating sleep apnea and encouraging better sleep patterns can improve blood glucose levels and prevent diabetes in African Americans.

For further information on this and other health topics, visit the web site of the National Institute of Health at www.nih.gov.