Working Long Hours Can Raise the Risk of This Disease

Working long hours can have detrimental effects on health — from increased stress to higher rates of certain chronic diseases. Now, in the latest study exploring the effect of extended work hours, researchers say that type 2 diabetes may be one of them.

Mahee Gilbert-Ouimet, an epidemiologist and postdoctoral fellow at the Institute for Work and Health in Toronto, and her colleagues analyzed data from a database of more than 7,000 workers in Canada who were followed for more than 12 years to better understand whether work hours can affect the risk of diabetes. In the study, published in BMJ Diabetes Research & Care, they report that women working more than 45 hours a week had a 51% higher risk of developing diabetes during the study period compared to women working 35 to 40 hours a week. (That was after the scientists adjusted for other potential factors that could affect diabetes risk, including physical activity, BMI and smoking.) They did not see the same effect in men; in fact, men working longer hours seemed to have a lower risk of developing diabetes compared to men working fewer hours.

“I was surprised to see the somewhat protective effect of longer working hours among men,” says Gilbert-Ouimet. “Among women, we know women tend to assume a lot of family chores and responsibilities outside the workplace, so one can assume that working long hours on top of that can have an adverse effect on health.” They found, for example, that the effect of longer working hours was stronger among women logging more than 45 hours a week at work who were living with children under age 12.

Another potential reason for the gender difference may have to do with the type of work men reported; in the study, about a third of the men working long hours said they spent that time doing a combination of sitting, standing and walking, compared to only 8% of the women who worked longer hours. The men’s higher level of physical activity may help to explain, in part, their lower risk of developing diabetes.

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The results add to the growing understanding of how work hours affect health, and especially diabetes. Previous studies found, as this one did, that people working longer hours seemed to have a higher risk of developing diabetes compared to those working fewer hours, but only among people with lower socioeconomic status. Most of the studies also included only men and not women. Gilbert-Ouimet and her team did not find a similar breakdown of risk by skill level, but she notes that there were few cases of diabetes among those with lower skilled jobs, and therefore their study may not have had the statistical power to pick up a valid trend.

The fact that long work hours may be connected to diabetes isn’t entirely surprising. People who work more than 40 hours a week may experience higher levels of stress, which can change hormones like cortisol. Changes in cortisol can affect the body’s insulin levels and its ability to break down sugar. Higher stress can also disrupt sleep and lead to poorer mental health, which in turn can contribute to changes in weight and insulin levels, and contribute to diabetes.

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Gilbert-Ouimet hopes that the results stimulate conversations among doctors and their patients about the role that long work hours can play in compromising health — especially among women who might already have other risk factors for developing diabetes. “I think physicians should ask the question of how many hours a week their patients work,” she says. “And if women also have risk factors, then they should discuss more followup visits or screening tests for diabetes.” She also says that given the new normal in which smartphones keep everyone tethered to work, “it’s a nice wake-up call to know what long hours can do to your body and to your health, and maybe force yourself to do a bit less and take care of yourself more.”