Sleep disordered breathing and circulating non-esterified fatty acids: the cardiovascular health study.

Study objectives: Circulating non-esterified fatty acids (NEFAs) have been associated with impaired glucose metabolism but their modifiable determinants remain uncertain. We sought to determine the association between objectively-measured sleep disordered breathing (SDB), which is also associated with dysglycemia, and NEFA levels among community-dwelling older adults.

Methods: We analyzed 787 older adults who had total fasting and post-load NEFAs measured in 1996-1997 in the Cardiovascular Health Study and underwent polysomnography between 1995 and 1997 in the Sleep Heart Health Study. We used multivariable linear regression to model NEFAs as a function of four SDB parameters: apnea-hypopnea index, arousal index, hypoxemia, and slow-wave sleep, and tested formal mediating effects by insulin sensitivity estimated with the Gutt index.

Results: The mean age of study participants was 77.5 ± 4.3 years. The proportion of females and non-Hispanic whites was 58.7 per cent and 84.2 per cent, respectively. We did not find statistically significant associations between any of the SDB parameters and fasting NEFAs, but higher amounts of slow-wave sleep were significantly associated in a linear fashion with lower total post-load NEFAs in unadjusted and adjusted models [adjusted: β = -0.004, SE = 0.001, p = .02]. In mediation analyzes, 10 per cent of the slow wave sleep-NEFA association was mediated by Gutt-estimated insulin sensitivity (p = .45 for the indirect effect).

Conclusions: Among the SDB measures studied, only higher levels of objectively measured slow-wave sleep were significantly associated with lower levels of post-load NEFAs, although the underlying mechanism is uncertain. Establishing a causal link would make SDB interventions a promising target for NEFA regulation.