Exercise Won't Prevent Diabetes in Postmenopausal Couch Potatoes

Though US patients spend an average of eight hours every day sitting in front of a television or computer, the amount of time they spend at rest increases even more with age. Public health agencies currently encourage 30 minutes of moderate-to-vigorous physical activity at least five days a week, but further research now suggests that exercise may not be enough to reverse the negative effects of sedentary behavior.

A recent statistical analysis on postmenopausal women has evaluated the association between self-reported daily sitting time and the incidence of type 2 diabetes.

Examining data from the Women’s Health Initiative observational study, the multi-center team of researchers identified 88,829 non-diabetic women who estimated the number of hours they spent sitting throughout a typical day. The researchers recognized incident cases of diabetes by using study subjects’ disclosures about taking insulin for diabetes. According to the study authors, a total of 7,416 women developed diabetes during the follow-up period.

After adjusting for demographics, health conditions, smoking, diet, alcohol intake, and family history of diabetes, the researchers found that each hour of sitting time was positively associated with an increased risk of diabetes, and in obese women, it was positively associated with incident diabetes. Obese women who reported sitting between eight and 11 hours per day were more likely to develop diabetes than women who sat for fewer than seven hours daily.

Remarkably, performing moderate-to-vigorous physical activity didn’t modify those associations, and the effect of sitting time on the women’s risk of diabetes was consistent even among those who reported exercising regularly.

“Our findings suggest that insulin resistance pathways might be further upregulated when obesity is combined with prolonged sitting,” the researchers concluded. The authors also suggested that “one 30-minute bout of moderate-to-vigorous intensity physical activity might not provide a sufficient stimulus to ward off the harmful metabolic effects of sitting.”