Women who work in rotating night shifts are more at risk for type 2 diabetes, according to a study by new research from the Harvard School of Public Health.

Researchers also say that workers with long durations of shift work are also more are also more likely to gain more weight than workers who work typical hours.

“The increased risk is not huge, but it's substantial and can have important public health implications given that almost one-fifth of the workforce is on some kind of rotating night shift,” said lead researcher Frank Hu, a professor of nutrition and epidemiology at Harvard.

The results from the study address potential risks for the 26 percent of the American working population that is involved in some sort of permanent night and rotating night shift work.

Hu explained that working irregular hours can disrupt the body's circadian rhythms. The circadian rhythms, also known as the body clock, help maintain healthy blood-sugar metabolism. The shift work schedule can disrupt the body’s ability to use insulin for breaking down sugars in the blood.

The researchers were most interested in the cumulative effect night work had on diabetes risk. They found that the longer people worked irregular hours, the higher their risk of developing the disease.

"It's something people should keep in mind," he told Time Magazine. "If they minimize or reduce the time they work on night shifts, they may be able to attenuate their risk."

The study consisted of data from around 177,000 middle-aged women who were enrolled in two Nurses’ Health Studies and followed for two decades. Those who worked rotating night shifts for 1 to 2 years increased their chances of developing diabetes by 5 percent over the next 20 years, compared with women who worked typical hours.

Women who worked for 10 to 19 years during the 20-year follow-up period increased their risk by 40 percent, and women who worked on and off night shifts for more than 20 years had a 60 percent chance of developing diabetes.

The researchers advise that there should be more research done on ways people can lower their risk for diabetes.

“Recognizing that rotating night shift workers are at a higher risk of type 2 diabetes should prompt additional research into preventive strategies in this group,” researchers said.