0810 School Year Circadian Timing is Associated with Insulin Resistance in Obese Girls

Abstract

Introduction: Over 33% of U.S. adolescents are obese and at risk for insulin resistance (IR). Insufficient sleep is highly prevalent in this age group. In adults, poor sleep health has been linked to IR, but data on this relationship are lacking in adolescents. Girls were chosen for study because they endorse more sleep complaints and have higher rates of type 2 diabetes (T2D) compared to boys. Our objective was to examine relationships between IR and circadian/sleep health in obese adolescent girls. Methods: Fifty-seven adolescent girls (15.7 ± 1.8 years) with BMI >;90%ile for age/sex were recruited from a tertiary weight-management specialty clinic. Participants underwent one week of objective home sleep monitoring with wrist actigraphy. Hourly-sampled evening and morning salivary melatonin, an oral glucose tolerance test, and polysomnography (N=31) occurred in laboratory. Correlations between circadian/sleep variables with IR were examined. Results: Girls overall were markedly insulin resistant and those who participated while in school were more IR and had shorter sleep duration than those on break. Longer sleep-onset latency, lower sleep efficiency, and earlier bedtime, waketime, and melatonin onset were associated with IR for participants on a regular school schedule, but not for those on school break. For participants on school schedule, wider phase angle of entrainment between dim-light melatonin onset and bedtime was significantly associated with IR (r=0.49, p=0.04). Higher apnea hypopnea index was strongly associated with IR regardless of being in school or on break (r=0.71, p<0.001). Conclusion: In this cohort of obese, IR, adolescent girls referred for obesity management, circadian timing correlated with IR and may be exacerbated by school-enforced early wake times. Future research in this population is urgently needed to investigate the impact of sleepand circadian-related interventions on prevention or treatment of IR and T2D.