Acute effects of night work and meals on blood glucose levels.

Employees working at night are at increased risk of diabetes. A possible mechanism is related to differences in glucose regulation at night. Laboratory simulated night work studies show regulation of blood glucose is impaired at night. Regular exposure to high glucose levels at night may explain the observed relationship between night work and diabetes. We performed a field study of 19 nonsmoking women from the health-care sector to investigate how night work and the composition of meals affect post-prandial blood glucose levels. Blood glucose levels were self-assessed by finger-prick blood sampling using the Beurer blood glucose monitoring system. Measurements were done before and 15, 30, 60, and 120 min after different test meals: a nighttime high sugar meal during a night shift and during a day shift, and a reference (low sugar) meal under these same two conditions. There was a statistically significant difference in blood glucose concentration between the four test meal conditions (P = .0086). Post-meal blood glucose levels following the night-shift meals, compared to following daytime meals, rose faster and remained elevated for longer a duration of time. At the 15 min time point following the high sugar test meal, the blood glucose concentration was 8.3 mmol/L when consumed at night vs. 7.3 mmol/L when consumed during the day. We found no difference in area under the blood glucose concentration-time curve (AUC) after consumption of the high or low sugar test meals during the night shift compared with consumption of them during the day. Our findings indicate the glucose levels in response to food intake by female night working healthcare assistants are higher following the nighttime compared with daytime consumption of a high sugar content meal. However, we did not find a difference in total glucose exposure across time (assessed as AUC) after eating a high vs. low sugar meal during the night shift.

The urinary 6-sulfatoxymelatonin level after three different work schedules with 2, 4 and 7 consecutive night shifts among Danish police officers.

Night shift work suppresses excretion of melatonin, but little is known about the needed time for recovery. We aimed to compare levels of 6-sulfatoxy melatonin after three different night shift schedules, including recovery days. In a quasi-experimental, within-subject crossover study, 73 male police officers in Denmark collected morning urine after the last recovery day in three different work schedules with two, four, and seven consecutive night shifts followed by a corresponding number of days for recovery. We found no significant differences for 6-sulphatoxymelatonin concentrations in morning urine between the three different work schedules indicating similar recovery of melatonin suppression in the studied work schedules.