Association of postprandial triglyceride responses with insulin resistance among rotational night shift healthcare workers.

NEW FINDINGS: What is the central question of this study? Does long-term rotational night shift work among healthcare workers alter postprandial triglyceride metabolism, and are the postprandial triglyceride responses associated with insulin resistance? What is the main finding and its importance? Rotational night shift duties in healthcare workers might have a negative impact on postprandial triglyceride responses and insulin sensitivity. This is the first study in which postprandial triglyceride responses among shift workers exposed to long-term night shifts have been studied. ABSTRACT: Studies on the postprandial period demonstrate that in experimental conditions, abrupt or acute changes in sleep timing and work are followed by significantly altered postprandial glucose, insulin secretion and lipid tolerance. Whether shift work results in altered postprandial triglyceride (PPTG) metabolism in the long term is not known. In the present study, we aimed to ascertain the association between PPTG and shift work in relationship to cardiometabolic risks and to compare the PPTG response among healthcare workers with and without night shift duties. Twenty healthcare workers with rotational night shifts (group 2) and 20 age- and sex-matched healthcare workers who had not done night shift duty in the past 1 year or ever (group 1) were recruited. Only subjects with normal glucose tolerance were recruited. A standardized fat challenge test was done in all study subjects. The postprandial triglyceride area under the curve (PPTG AUC) showed overall (n = 40) a significant positive correlation with fasting insulin and homeostatic model assessment of insulin resistance (HOMA-IR) (r = 0.40, P = 0.01 and r = 0.37, P = 0.01, respectively) and in group 2 (r = 0.49, P = 0.02 and r = 0.44, P = 0.042, respectively). The PPTG peak also showed a significant positive correlation with fasting insulin and HOMA-IR in group 2 (r = 0.52, P = 0.01 and r = 0.47, P = 0.03, respectively). No significant correlation was found in group 1. The PPTG AUC and PPTG peak were, however, comparable between both groups. The findings of this pilot study suggest that rotational night shift duties in healthcare workers might have a negative impact on metabolic parameters, including postprandial triglyceride responses and insulin sensitivity.