Working 45+ hours weekly may increase diabetes risk in women — But not men

TORONTO — Logging no more than seven to eight hours of work each day may be pivotal to women’s health. That’s because a recent study found that women who work more than 45 hours per week are at higher risk of developing diabetes compared to women who work less. 

The study, conducted by a team of Canadian researchers, showed that women who worked between 30 and 40 hours per week didn’t increase their risk of diabetes. Researchers think this may be a modifiable risk factor for women who are trying to stay healthy in their work and personal life. 

Diabetes affects millions around the world and is expected to increase in the years to come along with the cost of healthcare for this disease. It’s estimated that 439 million adults worldwide will have diabetes by 2030, which is up by 50% from 2010. Care for this disease comes at a high price and in 2015 the global cost of treatment was $1.31 trillion.   

Prior studies have linked one’s schedule to diabetes risk, but most of the research only used samples of men.

“Three out of the four previous studies on work hours and diabetes were limited by the inclusion of only men or women,” the authors write. “The current 12-year prospective study added new evidence on the importance of evaluating this relationship separately for both genders. Working 45 hours or more per week was associated with an increased incidence of diabetes among women, but not men.”

The study included 7,065 Canadians between the ages of 35 and 74 years, and tracked their health over 12 years via national health surveys and medical records. Other factors including their weekly working hours (paid and unpaid), sex, marital status, parenthood, ethnicity, place of birth and residence, long term health conditions, lifestyle and BMI were also taken into account. 

During the 12 years the participants were monitored, 1 in 10 developed type-2 diabetes. The diagnosis was more likely in men, older adults and those who were obese. 

Participants were slotted into one of four groups based on how many hours they worked weekly: 15-34 hours; 35-40 hours; and 45 or more hours. The type of work, whether the individual did shiftwork, the number of weeks worked in the past year and whether the job was active or sedentary were also included in the analysis.  

When the hours worked per week were analyzed, the risk of diabetes wasn’t highest among men. A longer working week actually meant less risk of diabetes in men. However, women who worked more than 45 hours per week were at a 63% higher risk than women who worked 35 to 40 hours per week. Even when other factors well associated with diabetes risk such as smoking, physical activity, alcohol consumption and BMI were taken into account, the women’s risk was only slightly reduced.  

Even with these findings the study has some limitations. Being an observational study, a cause and effect relationship can’t be established between working hours and disease. Researchers state there was no obvious explanation for the outcome differences between men and women. They offer an explanation for the findings saying that a chronic stress response may be triggered by working long hours, which would affect hormone and insulin resistance. They also suggest that women may actually work longer hours when household and family duties are taken into account. 

The study is published online in BMJ Diabetes Research and Care.

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About the Author

Jamie Sculley

Dr. Jamie Sculley is a licensed naturopathic doctor practicing in Washington state. She specializes in treating thyroid disease, allergies, digestive issues and anxiety. She writes a weekly blog on these topics which can be found on her website at

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