Rotating night shift work linked to increased risk of type 2 diabetes in women, revealed by Harvard researchers. Extended years of rotating night shift work was associated with weight gain, which may contribute to the increased risk of type 2 diabetes.
Women who work a rotating or irregular office-schedule that includes three or more night shifts per month, in addition to day and evening working hours in that month, may have an increased risk of developing type 2 diabetes.
This study is the largest study so far to look at the link between shift work and type 2 diabetes and the first large study to follow women.
The researchers analyzed data on more than 69,269 U.S. women, ages 42 to 67, tracked from 1988 to 2008, and 107,915 women, ages 25 to 42, tracked from 1989 to 2007.
The researchers found that the longer women worked rotating night shifts, the greater their risk of developing type 2 diabetes. Those women who worked rotating night shifts for three to nine years faced a 20% increased risk; women who worked nights for 10 to 19 years had a 40% rise in risk; and women who worked night shifts for over 20 years were 58% more at risk. In addition, women who worked rotating night shifts gained more weight and were more likely to become obese during the follow-up.
This study raises the awareness of increased obesity and diabetes risk among night shift workers and underscores the importance of improving diet and lifestyle for primary prevention of type 2 diabetes in this high risk group.
“Long-term rotating night shift work is an important risk factor for the development of type 2 diabetes and this risk increases with the numbers of years working rotating shifts,” said An Pan, research fellow in HSPH’s Department of Nutrition and the study’s lead author.