1062 DO HABITUAL SLEEP PATTERNS MEDIATE THE RELATIONSHIP BETWEEN BODY MASS INDEX AND TYPE-2 DIABETES? RESULTS FROM A POPULATION SAMPLE

Abstract Introduction: Sleep duration and timing have independently been associated with body mass index (BMI) and type-2 diabetes (T2D). The extent to which sleep duration mediates the relationship between BMI and T2D for each sleep timing category (morning, intermediate, evening) remains unclear. Disentangling the complex relationship between sleep duration, timing, BMI, and T2D could shed light on sleep as intervention targets for reducing T2D risk among those with higher BMI. Methods: Baseline data from the UK Biobank cohort study (N=109,397) were used to generate multigroup path analysis models to identify the direct, indirect, and total effects through which sleep duration (short ≤6hrs; adequate 7-8hrs; long ≥9hrs) mediates the relationship between BMI and T2D, for each sleep timing category. All pathways were adjusted for socio-demographic and cardiovascular risk factors. Model fit was assessed. Results: Most participants were white (92%), female (55%) and did not attend college (66%). Short sleep duration was reported by 24%, adequate by 68% and long by 8%. Twenty-eight percent of the sample were morning, 64% were intermediate and 8% were evening type. The path models demonstrated small but statistically significant mediation for morning and intermediate types. Among morning types, short (versus adequate) sleep mitigated T2D as BMI increased (β=-0.001, p=0.032). Among intermediate types, long (vs. adequate) sleep exacerbated T2D as BMI increased (β=0.0004, p=0.005). The model provided a good fit to the data (CFI=0.998, TLI=0.839, RMSEA=0.013, WRMR=0.538). Conclusion: These data provide preliminary evidence that short sleep in morning type persons may not always be deleterious with regard to the BMI-T2D relationship. On the other hand, long sleep in intermediate type persons may be indicative of a worsened BMI-T2D relationship. Prospective work is needed to validate these findings and to examine the effects of sleep duration adjustment, for different sleep timing subgroups, on BMI and T2D outcomes. Support (If Any): N/A