0297 Pathways: A Pilot Study Examining the Impact of Nightshift Work on Obesity and Type 2 Diabetes Risk in Free-Living Shift Workers

Abstract

Abstract Introduction Traditional risk factors for obesity and type 2 diabetes, such as poor diet and low physical activity, cannot fully explain the increased incidence of these diseases. Insufficient sleep and circadian misalignment due to shift work may contribute, in part, to this epidemic through their growing prevalence and associated impaired glucose regulation and eating out of phase. Methods Female nightshift healthcare workers (n=5) worked ≥2 shifts (~7pm-7am) during the 7-day study. Actigraphy was measured and participants wore continuous glucose monitors and completed three 24-hour dietary recalls. Dim light melatonin onset was predicted (pDLMO) for each worker from an actigraphy derived algorithm validated for shift workers. The timepoints two hours after (pDLMO+2) and 10 hours after (pDLMO+10) predicted DLMO are presented as a range in which sleep typically occurs, on average, relative to DLMO. Results Mean participant age was 30.7 years and body mass index 22.8 kg/m2. Dietary recalls report the average total energy consumed on workdays to be 1,653 kcal ± 444 (mean ± SD) compared to 1,517 kcal ± 421 on free days (p=0.64). Average eating windows were 13.88 ± 2.69 hours on nightshifts compared to 9.88 ± 1.82 hours on workfree days (p=0.051, n=4 one individual did not report eating while on shift). Further, eating occasions between 10pm–7:30am were only reported on worknights. Average pDLMO was 23.26 ± 1.27 hours, corresponding to the middle of shift. The average interstitial glucose level between pDLMO+2 and pDLMO+10 on shift was 88.4 mg/dL ± 9.0 and the average during the same interval on workfree nights was 81.1 mg/dL ± 7.0 (p = 0.024). Additionally, an increase in 24-hour average glucose was observed on shift 90.9 ± 4.9 compared to free days 86.1 ± 6.2 (p=0.021). Conclusion Early results from this ongoing study show that an extended eating window, eating overnight, and/or working overnight contribute to increased glucose levels while night workers are on shift compared to their days off. Increased overnight glucose levels, especially at a time the body may be accustomed to sleeping, represent a time of impaired glucose tolerance and potentially reduced insulin sensitivity. Support (if any) Anschutz CCTSI Pilot Grant Award, CTSA Grant UL1 TR002535