8290977 Night shift work may impair glucose levels at night: a field study among female hospital employees

<h3>Objective</h3> Alternating around-the-clock work schedules disrupt the natural circadian rhythms, resulting in circadian misalignment that increases risks for metabolic and cardiovascular diseases. How night shift work affects glycemic profiles in real-world settings remains to be settled. We hypothesized that working during the night impairs glucose levels among female hospital employees compared to shift work during the day. <h3>Material and Methods</h3> The study employs an observational design in which a subgroup of the 1001 nights-cohort in Denmark of 57 female hospital employees without known diabetes were found eligible to register working hours, sleep, and food intake in diaries while wearing a Continuous Glucose Monitor (CGM, Dexcom) for seven days. A night shift was defined as working 8 hours from 23:00 to 07:00, and a day shift as working 8 hours from 07:00 to 15:00. A ‘night off’ and a ‘day off’ were defined as not working during these intervals. The study included 39 participants, each having (1) at least one night shift and off night and/or (2) at least one day shift and off day. Thirty-five participants had both. Daily mean and standard error of glucose levels at night and day shifts and at off nights and days were calculated. <h3>Results</h3> Participants completed a total of 76 night shifts and 276 nights off, along with 72 day shifts and 246 days off. The mean glucose levels were 116.0 (SEM 1.9) mg/dL during night shifts, 113.2 (SEM 0.9) mg/dL during nights off, 111.7 (SEM 1.6) mg/dL during day shifts, and 111.7 (SEM 1.0) mg/dL during days off. <h3>Conclusion</h3> Shift work may modestly increase mean glucose levels at night but not at daytime. Results of other CGM-derived outcome variables and ongoing statistical variance component modeling using the within-person design will be presented at the conference. <h3>Funding</h3> The Danish Working Environment Research Fund (26202009; 19202209), The Health Foundation (22B0452), the European Union’s Horizon (# 874703), NFA, and The Danish Cardiovascular Academy.