Night shift associated with type 2 diabetes risk in US women

Women in the US working a rotating night shift have a modestly increased risk of type 2 diabetes, according to a research article published in the journal PLoS Medicine.

“These findings show that in these women, there is a positive association between rotating night shift work and the risk of developing type 2 diabetes. Furthermore, long duration of shift work may also be associated with greater weight gain,” according to the article.

Researchers from Harvard Medical School analyzed data from the Nurses' Health Study in 1976 and 1989, in which more than 235,000 women provided information about their lifestyle, medical conditions, and history of rotating night shifts work. The control group of women did not have a history of rotating night shift work, which is defined as three or more night shifts in a month, plus at least 19 day and evening shifts in that month.

The data showed that the risk of developing type 2 diabetes increased with the number of years working rotating shifts.

This increased risk is partly mediated through body weight, according to researchers. They say that previous studies suggest that rotating night shift work is associated with an increased risk of obesity and metabolic syndrome, which are both closely linked to type 2 diabetes.

“Proper screening and intervention strategies in rotating night shift workers are needed for prevention of diabetes,” according to the article.

About 346 million people in the world have diabetes, according to the article. An estimated 3.4 million people died in 2004 from complications of high blood sugar. Type 2 diabetes accounts for 90 percent of people with diabetes and is largely the result of excess body weight and physical inactivity, which causes the body to use insulin ineffectively.

Source: PLoS Medicine