Abstract
INTRODUCTION: Night shift work has been associated with obesity, cardiovascular diseases, and certain cancers. The primary objective of this study was to assess the differences in metabolic and endocrine profiles between night shift and day shift workers in a South Indian cohort. METHODS: This cross-sectional study included 45 night shift workers (NSWs) and 45 day shift workers (DSWs). Metabolic parameters measured were HOMA IR, HDL-C, triglycerides, adiponectin, free fatty acids, and BMI. Hormonal parameters measured were total T3, total T4, TSH, 8 am cortisol, LH, FSH, testosterone, oestradiol, growth hormone, IGF-1, and 25 (OH) vitamin D(3). RESULTS: NSWs were younger (28.6 ± 5.7 years vs. 31.1 ± 7.2 years; P = 0.022) with a lower mean BMI (24.2 ± 5 kg/m(2) vs. 25.2 ± 5.7 kg/m(2); P = 0.33) and higher mean HOMA IR (6.3 ± 5.4 vs. 5.2 ± 4.4; P = 0.26). 77% (n = 35) of NSW had HOMA-IR ≥ 2.5 in comparison to 62% (n = 28) of DSW (P = 0.031). NSW had higher median triglycerides (195([90]) mg/dl vs. 180([44]) mg/dl; P = 0.045) and lower mean HDL-C levels (35 ± 2.7 mg/dl vs. 40 ± 3 mg/dl; P < 0.001). NSW males had lower mean LH levels (2.8 ± 1.4 mIU/ml vs. 5.6 ± 3 mIU/ml; P = <0.001) and testosterone levels (373.6 ± 146 ng/dl vs. 400 ± 140 ng/dl; P = 0.5). The mean oestradiol levels were elevated in female NSW (181 ± 84 pg/ml vs. 100 ± 62 pg/ml; P = 0.006). 25(OH) vitamin D(3) levels were significantly low in the NSW (10.4 ± 4.8 ng/ml vs. 13.7 ± 4.5 ng/ml; P = 0.032). CONCLUSION: The present study shows night shift work is associated with increased risk of insulin resistance, hypertriglyceridemia, low HDL-C, low LH and testosterone in males, high oestradiol among females, and vitamin D deficiency.