Elevated cardiometabolic risk markers in evening chronotype shift workers: a case–control study in male workers

Shift work-induced circadian disruption has been linked to various cardiometabolic diseases, including obesity, diabetes and CVD. Limited studies have explored the impact of different variables such as night work durations, intensities and chronotype on cardiometabolic risk. This study aimed to determine the impact of circadian disruption on cardiometabolic risk markers in shift workers. This case-control study was conducted with 104 male workers (shift workers; <i>n</i> 52, mean age; 43·3 (sd 10·2), and non-shift workers; <i>n</i> 52, mean age; 41·2 (sd 9·8)). Shift work details were determined via an interviewer-administered questionnaire. Cardiometabolic risk was evaluated through anthropometric (height, weight, waist circumference and body composition), biochemical (fasting glucose and lipid profile), clinical (blood pressure) and dietary assessment (24-h recalls from working and non-working days). The chronotype was determined via the Munich Chronotype Questionnaire (MCTQ). Shift workers had significantly higher mean body fat percentage (31·7, 22·7 % <i>P</i> = 0·031), systolic blood pressure (SBP) (138·6, 128·5 mmHg <i>P</i> = 0·009), pulse rate (78·7, 72·3 bpm <i>P</i> = 0·015), TAG (1·60, 1·30 mmol/l <i>P</i> = 0·021) and LDL-cholesterol (3·90, 3·40 mmol/l <i>P</i> = 0·012) than non-shift workers. Evening chronotype shift workers had significantly higher visceral fat levels (12·8, 8·90 <i>P</i> = 0·001), SBP (137·0, 127·6 mmHg <i>P</i> = 0·006), pulse rate (82·7, 73·3 bpm <i>P</i> = 0·005) and LDL-cholesterol (4·00, 3·40 mmol/l <i>P</i> = 0·039) than shift workers with a morning chronotype. In conclusion, shift workers exhibited higher metabolic risk markers than non-shift workers. Shift workers with evening chronotypes had higher cardiometabolic risk than morning chronotypes. Further research is warranted to elucidate the underlying mechanisms and inform targeted interventions for individuals engaged in shift work, considering chronotypes.