WEDNESDAY, Sept. 24, 2014 (HealthDay News) -- Working long hours may increase your risk for diabetes, a new study suggests. But the finding seems to depend on your job.
Researchers examined data from prior studies involving more than 222,000 men and women in the United States, Europe, Japan and Australia who were followed for an average of 7.6 years.
The initial analysis revealed no difference in the risk of type 2 diabetes among people who worked more than 55 hours a week and those who worked 35 to 40 hours a week.
However, further analyses showed that people who worked more than 55 hours a week at manual labor or other types of "low socioeconomic status jobs" were 30 percent more likely to develop diabetes than those who worked 35 to 40 hours a week.
This increased risk remained even after the researchers accounted for diabetes risk factors such as smoking, physical activity levels, age, sex and obesity, and after the researchers excluded shift work, which increases the risk of obesity and diabetes.
Although the study, published Sept. 24 in The Lancet Diabetes & Endocrinology, found an association between long work weeks and diabetes, it didn't establish a cause-and-effect relationship.
Further research is needed to learn more about the seeming link between working long hours and increased diabetes risk, the study authors said.
Possible explanations include the fact that people who work long hours have little time for healthy behaviors such as exercise, relaxation and adequate sleep.
"Although working long hours is unlikely to increase diabetes risk in everyone, health professionals should be aware that it is associated with a significantly increased risk in people doing low socioeconomic status jobs," Mika Kivimaki, professor of epidemiology at University College London in England, said in a journal news release.
The authors of an accompanying journal commentary said the findings may have implications for diabetes-prevention programs.
The study findings remained strong "even after controlling for obesity and physical activity, which are often the focus of diabetes risk prevention, suggesting that work factors affecting health behaviors and stress may need to be addressed as part of diabetes prevention," Dr. Orfeu Buxton, of Pennsylvania State University, and Dr. Cassandra Okechukwu, from Harvard School of Public Health, wrote.