Diabetes link to sitting largely due to obesity and lack of exercise

Too much time spent sitting is associated with an increased risk of developing diabetes, but the effect is primarily seen among those who are also obese or inactive most of the time, a recent Danish study finds.

Overall, the study linked sitting for more than 10 hours a day to a 35 percent higher risk of diabetes compared with sitting for less than 6 hours daily.

But the good news for desk jockeys is that staying slim and getting plenty of exercise appeared to minimize the diabetes risk associated with all that time sitting down.

"If you are normal weight, and it's impossible to avoid sitting a lot at work, it's nice to know that being physically active outside work alleviates the diabetes hazard from sitting - at least that's what our results point toward," said senior study author Dr. Janne Tolstrup of the University of Southern Denmark in Copenhagen.

While previous research has linked sedentary time to diabetes, the current findings should encourage people with desk jobs to get moving more during the day, Tolstrup added by email.

"If you do sit, there's a lot you can do quite easily," Tolstrup said. "Stand at your desk, or try to vary your position, take active breaks such as standing or walking as opposed to sitting, and be sure you have some real physical activity during leisure time."

Globally, about one in 10 adults have diabetes, according to the World Health Organization. Most of these people have type 2 diabetes, which is associated with obesity and aging and occurs when the body can't make or use enough of the hormone insulin.

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To assess the connection between diabetes and sedentary time, Tolstrup and colleagues analyzed data on more than 72,000 people who reported how much time they spent sitting in 2007 and 2008. The researchers followed people over five years to see how many developed diabetes.

Half of the study participants reported sitting for at least 6.3 hours a day, according to the results in the British Journal of Sports Medicine.

People who reported sitting for 10 hours or more were likely to be younger, have more education, be physically inactive, smoke, drink alcohol and be overweight.

During the study period, 1,790 adults developed diabetes.

Compared to those who sat for less than six hours a day, people who spent six to 10 hours sitting were 15 percent more likely to develop diabetes, suggesting the risk increases with the number of hours spent sitting down.

There wasn't an increased diabetes risk associated with increased sitting time when people got at least 150 minutes a week of moderate to vigorous physical activity, however. That suggests that other factors - notably obesity and lack of exercise - are the main drivers of the link between sitting time and diabetes risk, the study team writes.

Limitations of the study include its reliance on people to accurately report how much time they spent sitting on a typical day, as well as the lack of data on their sedentary habits over time, the authors note. Only 14 percent of people asked to participate agreed to join the study, which also means the results may not be representative of the Danish population.

"Unfortunately at the population level, the majority of the population are overweight or obese and the majority of the population are inactive," said David Dunstan, head of the physical activity laboratory at Baker IDI Heart and Diabetes Institute in Melbourne, Australia.

"The message here is that health gains could be made at the population level if sitting time was reduced, of course, in addition to engaging in regular exercise," Dunstan, who wasn't involved in the study, added by email.

Certainly, there's little downside to getting up from a desk to walk around, said Bethany Barone Gibbs, a researcher at the University of Pittsburgh who wasn't involved in the study.

"It is unlikely that reducing sitting and breaking it up will be harmful, but we are still trying to quantify the potential benefit of this particular behavior modification on diabetes risk and other health outcomes," Gibbs said by email.