Sleep-disordered breathing and fragmented sleep are associated with higher levels of fasting glucose and hemoglobin A1c (HbA1c) in black adults both with and without diabetes, according to results of the Jackson Heart Study published in the Journal of the American Heart Association.
Previous studies have reported a higher prevalence of insulin resistance and type 2 diabetes in black men and women compared with white patients. Disrupted sleep is known to be associated with abnormal blood glucose levels, but few studies have used objective measurements of sleep characteristics to assess their association with blood glucose levels in black adults.
To evaluate this, researchers used data from participants in the Jackson Heart Study, a community-based, prospective cohort study of black men and women. Sleep measurements were examined for their associations with blood glucose levels, and the results were reported as standardized regression coefficients (betas) for each standard deviation (SD) higher level in each sleep measure.
The cross-sectional analyses included data on 789 individuals (mean age, 63 years; 74% women; 25% with diabetes) who completed home sleep apnea testing and 7-day wrist actigraphy between 2012 and 2016. Sleep-disordered breathing measurements included respiratory event index (REI) associated with 3% (REI3P) or 4% (REI4P) oxygen desaturation and overnight hypoxemia. Sleep patterns on actigraphy included fragmented sleep indices, as well as sleep duration, sleep maintenance efficiency, and night-to-night variability of sleep duration.
After multivariable adjustment, higher REI3P, REI4P, and fragmented sleep index were all significantly associated with higher levels of fasting glucose and HbA1c. The betas for each SD higher level in REI4P were 0.13 mmol/L (95% CI, 0.02-0.24) for fasting glucose and 1.11 mmol/mol (95% CI, 0.43-1.78) for HbA1c. For each SD increase in fragmented sleep indices, the betas were 0.16 mmol/L (95% CI, 0.05-0.27) for fasting glucose and 0.77 mmol/mol (95% CI, 0.10-1.43) for HbA1c.
Insulin resistance was estimated using the homeostatic model assessment of insulin resistance (HOMA-IR). In 589 individuals without diabetes, higher REI3P, REI4P, and fragmented sleep indices and lower minimum oxygen saturation and sleep maintenance efficiency were each significantly associated with higher HOMA-IR. The betas for each SD higher level were 1.09 (95% CI, 1.03-1.16) for REI4P, 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.
The study had several limitations, including the cross-sectional design, potential residual confounders such as physical activity and diet, and that only a subset of participants in the original Jackson Heart Study underwent sleep assessments.
“Further studies are needed to determine whether improvement of sleep apnea (eg, continuous positive airway pressure) and sleep patterns (eg, sleep regularity) could improve glycemic control and reduce insulin resistance, and whether modification of sleep habits could be used as an adjunct treatment to antihyperglycemic therapy for people with diabetes mellitus,” wrote the researchers.
Yano Y, Gao Y, Johnson DA, et al. Sleep characteristics and measures of glucose metabolism in blacks: the Jackson Heart Study. J Am Heart Assoc. 2020;9:e013209.