Both rotating night shift work and unhealthy lifestyle were associated with a higher risk of type 2 diabetes (T2D) in 2 large US cohorts of female nurses. The prospective cohort study included 143,410 women from the Nurses’ Health Study (1988-2012) and Nurses’ Health Study II (1991-2013), without T2D cardiovascular disease (CVD), or cancer at baseline. Rotating night shift work was defined as at least 3 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 (BMI) of ≥25. Researchers found:

• During 22-24 years of follow-up, 10,915 cases of incident T2D occurred.
• Duration of rotating night shift work and unhealthy lifestyle were independently and jointly associated with a higher risk of T2D.
• Most cases of T2D could be prevented by adherence to a healthy lifestyle.