Rotating night shifts and unhealthy lifestyle factors are independently and jointly associated with a higher risk of type 2 diabetes mellitus (T2DM), research in the BMJ has shown (21 November 2018)
The study used data from the Nurses’ Health Studies I and II on 143,410 women without T2DM at baseline who were followed up for 22–24 years.
Working rotating night shifts (at least three night shifts per month) was independently associated with the risk of developing T2DM, with each five-year duration linked to a 31% higher risk. Each unhealthy lifestyle factor, such as smoking, following a low-quality diet, having low levels of physical activity and being overweight or obese, was associated with a 130% higher risk of T2DM.
However, among women who worked rotating night shifts, each individual unhealthy lifestyle factor was associated with a 183% higher risk, indicating an additive interaction.
The researchers said the findings indicate that the benefits of adhering to a healthy lifestyle could be even greater in people who work rotating night shifts.
“Our findings suggest that most cases of T2DM could be prevented by adherence to a healthy lifestyle,” they wrote.
“Further studies are warranted to confirm our findings and clarify the underlying mechanisms.”
 Shan Z, Li Y, Zong G et al. 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. BMJ 2018;363:k4641. doi: 10.1136/bmj.k4641