Is Shift Work Associated with Lipid Disturbances and Increased Insulin Resistance?

Objective: Shift work is associated with higher risk of metabolic disturbances and cardiovascular diseases. There are contradictory reports on the effect of shift work on lipid parameters in the literature. No studies have investigated any possible association between shift work and the ratio of serum triglyceride to high density lipoprotein cholesterol (TG/HDL-C ratio). This ratio can be used as a predictor for insulin resistance. The main aim of the present cross-sectional study was to investigate the association between shift work and serum TG/HDL-C ratio, TG level, and HDL-C level. Methods: One hundred and forty adult Jordanian employees were recruited. Demographic data, lifestyle habits, clinical parameters, and working patterns data were documented through a well-structured questionnaire. Serum TG and HDL-C levels were measured after at least 9 hours fasting using enzymatic assay procedure. Results: Compared with daytime workers (58 subjects), shift workers (82 subjects) displayed higher TG/HDL-C ratio (r=0.217, P=0.013), higher serum TG levels (r=0.220, P=0.012), and lower HDL-C levels (r=-0.200, P=0.016). Among shift workers, 30.5% were found to have a TG/HDL-C ratio >3.5 compared with 8.6% of daytime workers (P=0.002). Conclusion: In the present study, shift work was shown to be associated with higher TG/HDL-C ratio, higher serum TG, and lower HDL-C levels. These findings might indicate that shift work is associated with increased insulin resistance and consequently higher risk of metabolic syndrome and cardiovascular diseases.