Sleep Apnea Could Contribute to Development of Diabetes in African-Americans

Yuichiro Yano, MD, PhD

New research from the Jackson Heart Study has uncovered a startling link between the presence of severe sleep apnea and increased blood glucose in African-Americans.

Results of the study, which was funded in part by the National Heart, Lung, and Blood Institute (NHLBI), suggested better sleep control could prove useful in improving blood glucose control and preventing type 2 diabetes among African-Americans.

"The study underscores the importance of developing interventions to promote regular sleep schedules, particularly in those with diabetes," said lead investigator Yuichiro Yano, MD, PhD, researcher in the Department of Family Medicine and Community Health at Duke University, in a statement. "It also reaffirms the need to improve the screening and diagnosis of sleep apnea, both in African Americans and other groups."

To further evaluate the impact of sleep apnea on blood glucose levels, Yano and a team of colleagues designed a cross-sectional analysis using information from the Jackson Heart Study, which was a community-based, prospective cohort study that included data on more than 5000 noninstitutionalized black patients 21 years of age and older. For the purpose of their study, the cohort was restricted to 789 patients who completed a sleep study after the third clinical visit.

Patients included in the current analysis completed an at-home sleep apnea test and had data from a wrist actigraph watch that was worn for 7 days. From the actigraph and sleep apnea test investigators were able to obtain measurements related to sleep duration, sleep efficiency, night-to-night variability in sleep duration, and sleep fragmentation. In total, patients were assessed across 8 different sleep characteristic exposures for 3 different glucose metabolism outcomes.

For the purpose of comparison, investigators created 4 groups to classify patients based on severity of their sleep apnea—mild, moderate, severe, and no sleep apnea. Mild sleep apnea was defined as between 5-14 respiratory index events (REI), 14-29 REI as moderate sleep apnea, and 30 or more REI as severe sleep apnea.

Of note, investigators were also able to obtain information related to age, sex, education level, height, weight smoking, alcohol use, medication use, and history of diabetes mellitus and cardiovascular disease for patients included in the analysis.

At baseline, the mean age of the study cohort was 63 (11) years, 74% were women, 25% had diabetes mellitus, and 20% were taking an antihyperglycemic medication. Investigators also noted mean BMI was 31.9 (6.9), 8% of participants were current smokers, and 34% were habitual drinkers.

Results of the multivariable-adjusted analysis indicated the betas for fasting glucose and HbA1c, respectively, each SD higher level were 0.13 (95% CI, 0.02-0.24) mmol/L and 1.11 (95% CI, 0.42-1.79) mmol/mol for REI associated with 4% oxygen desaturation and 0.16 (95% CI, 0.05-0.27) mmol/L and 0.77 (95% CI, 0.10-1.43) mmol/mol for fragmented sleep indices.

In a subgroup analysis of 589 patients without diabetes mellitus at baseline, results indicated the betas for homeostatic model assessment of insulin resistance for each SD higher level were 1.09 (95%CI, 1.03-1.16) for REI associated with 4% oxygen desaturation, 0.90 (95% CI, 0.85-0.96) for minimum oxygen saturation, and 1.07 (95% CI, 1.01-1.13) for fragmented sleep indices.

This study, “Sleep Characteristics and Measures of Glucose Metabolism in Blacks: The Jackson Heart Study,” was published in the Journal of the American Heart Association.