Rotating night shift work and adherence to unhealthy lifestyle in predicting risk of type 2 diabetes: results from two large US cohorts of female nurses

• Published in: BMJ (Online) 2018-11, Vol.363, p.k4641-k4641
• Main Authors: Shan, Zhilei, Li, Yanping, Zong, Geng, Guo, Yanjun, Li, Jun, Manson, JoAnn E, Hu, Frank B, Willett, Walter C, Schernhammer, Eva S, Bhupathiraju, Shilpa N
• Format: Article
• Language: English
• Subjects: Body mass index; Body weight; Cancer; Cardiovascular disease; Cardiovascular diseases; Circadian rhythm; Consortia; Diabetes; Diabetes mellitus; Diabetes mellitus (non-insulin dependent); Diet; Fatty acids; Food; Lifestyles; Metabolism; Metabolites; Microbiota; Nighttime; Nurses; Nutrient deficiency; Nutrition research; Obesity; Overweight; Physical activity; Questionnaires; Shift work; Smoking; Womens health; Workers
• ISSN: 0959-8138; 1756-1833
• DOI: 10.1136/bmj.k4641

To prospectively evaluate the joint association of duration of rotating night shift work and lifestyle factors with risk of type 2 diabetes risk, and to quantitatively decompose this joint association to rotating night shift work only, to lifestyle only, and to their interaction. Prospective cohort study. Nurses' Health Study (1988-2012) and Nurses' Health Study II (1991-2013). 143 410 women without type 2 diabetes, cardiovascular disease, or cancer at baseline. Rotating night shift work was defined as at least three night shifts per month in addition to day and evening shifts in that month. Unhealthy lifestyles included current smoking, physical activity levels below 30 minutes per day at moderate to vigorous intensity, diet in the bottom three fifths of the Alternate Healthy Eating Index score, and body mass index of 25 or above. Incident cases of type 2 diabetes were identified through self report and validated by a supplementary questionnaire. During 22-24 years of follow-up, 10 915 cases of incident type 2 diabetes occurred. The multivariable adjusted hazard ratios for type 2 diabetes were 1.31 (95% confidence interval 1.19 to 1.44) per five year increment of duration of rotating night shift work and 2.30 (1.88 to 2.83) per unhealthy lifestyle factor (ever smoking, low diet quality, low physical activity, and overweight or obesity). For the joint association of per five year increment rotating night shift work and per unhealthy lifestyle factor with type 2 diabetes, the hazard ratio was 2.83 (2.15 to 3.73) with a significant additive interaction (P for interaction