Working nights significantly increases African-American women’s risk of developing diabetes, new research shows.
The findings carry “important public health implications” given the high number of women affected, concluded the study’s authors, researchers from Boston University’s Slone Epidemiology Center.
Researchers stressed that the study wasn’t designed to prove that working nights causes diabetes ““ only that there’s an association between the two.
For the study, researchers reviewed data from more than 28,000 African-American women in the U.S. who were diabetes-free in 2005; 37 percent of the women worked nights, and 5 percent said they had worked nights for at least 10 years.
Over the next eight years, nearly 1,800 cases of diabetes were diagnosed among the larger group of women. Compared to women who never worked night shifts, women who worked nights for one to two years had a 17 percent higher risk of developing diabetes. After three to nine years, the risk for developing diabetes jumped to 23 percent, and after 10 years or more, women who worked nights were 42 percent more at risk for developing diabetes than women who worked days, researchers found.
African-American men and women are more likely to work nights than Caucasian men and women researchers noted; 35 percent compared to 28 percent.
After adjusting for differences in body mass index and lifestyle factors such as smoking and diet, researchers found African-American women who worked nights were still at greater risk for developing diabetes than women who worked days.
The link between night shift and diabetes was stronger in younger women than in older women. Compared to never working the night shift, working night shifts for 10 or more years increased the risk of diabetes by 39 percent among women younger than 50 and by 17 percent among those 50 and older.
Diabetes is more prevalent among African Americans than Caucasians in the U.S. Nearly 13 percent of African-American women have diabetes, compared to 4.5 percent of Caucasian women.
The findings suggest that weight and lifestyle factors like diet and tobacco use aren’t the only factors at play in the development of diabetes, researchers said. Night shift work disrupts the body’s sleep-wake cycle, and the disruption’s effects on the body’s metabolism are “profound,” the study said. More research is needed to zero in on the specific mechanism that might be responsible for the difference in prevalence, researchers said, as well as to find ways to reduce the overall risk for diabetes among night shift workers.
The study was published in January in Diabetologia.
