Boston, MA -- Women who work a rotating (irregular) 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 when compared with women who only worked days or evenings, according to a new study led by researchers at Harvard School of Public Health (HSPH). In addition, the researchers found that extended years of rotating night shift work was associated with weight gain, which may contribute to the increased risk of type 2 diabetes.
Previous studies have focused on the association between shift work and risk of cancer and cardiovascular disease. The HSPH 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 findings were published online December 6, 2011 in the open access journal PLoS Medicine.
"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.
The researchers, led by Pan and senior author Frank Hu, professor of nutrition and epidemiology, analyzed data on more than 69,269 U.S. women, ages 42 to 67, in the Nurses' Health Study I, tracked from 1988 to 2008, and 107,915 women, ages 25 to 42, in the Nurses' Health Study II, tracked from 1989 to 2007. About 60% of the nurses performed more than one year of rotating night shift work at baseline; about 11% in Nurses' Health Study I had more than 10 years of rotating night shift work at baseline, and about 4% in Nurses' Health Study II worked more than 10 years of rotating night shifts at baseline, and this proportion increased during the follow-up.
The researchers found that the longer women worked rotating night shifts, the greater their risk of devel
|Contact: Marge Dwyer|
Harvard School of Public Health