Effect of Vigorous Exercise on Type 2 Diabetes Risk

Vigorous-intensity exercise, either alone or combined with moderate-intensity exercise, can reduce the risk of developing type 2 diabetes mellitus (T2DM), according to a large study among Japanese workers.

Physical activity is considered a key strategy for the prevention of T2DM. Based on epidemiological evidence mainly on leisure-time physical activity for health, including diabetes prevention, US and international guidelines recommend adults engage in at least 150 minutes per week of moderate-intensity physical activity, 75 minutes per week of vigorous-intensity physical activity, or an equivalent combination of the two intensities.

These researchers, led by Toru Honda of the Hitachi Health Care Center in Hitachi, Japan, and Keisuke Kuwahara of the National Center for Global Health and Medicine in Tokyo, Japan, examined the associations between leisure-time, occupational, and commuting physical activity and the risk of T2DM in a working population, with a special emphasis on the intensity and dose for leisure-time physical activity.

The study included 26,628 workers (23,207 men and 3,421 women), median age 45 years, without diabetes at baseline. Leisure-time exercise, occupational physical activity, and duration of walking to and from work were self-reported. Diabetes was diagnosed by using HbA1c, fasting or random blood glucose, and self-reported.

More than one-third of the participants walked to work and worked overtime hours, and 18.8% engaged in shift work.

Compared with workers who engaged in a lower dose of leisure-time exercise, those who engaged in a higher dose of leisure-time exercise were older, had a higher BMI, tended to engage in sedentary work, and slept more, but were less likely to be a female, a shift worker or a smoker, and walked less during commuting, the researchers stated.

During a mean follow-up of 5.2 years, 1,770 participants developed T2DM. “There was a significant inverse association between the dose of leisure-time exercise and the risk of type 2 diabetes in the age- and sex-adjusted model,” the researcher stated. “Vigorous-intensity exercise alone or vigorous-intensity exercise combined with moderate-intensity exercise yielded greater health benefits in terms of risk reduction for incident diabetes compared with moderate-intensity exercise alone at the same dose of activity.”

The researchers noted that only 2 US cohort studies have found that any increase in the dose of physical activity from a sedentary level can reduce the risk of T2DM. But these findings are limited due to the potential mixing of activities with different intensities.

“In the present study, engagement in vigorous-intensity exercise alone and both moderate- and vigorous-intensity exercise below the recommended dose (7.5 MET-hours per week) had an approximately 30% lower risk of diabetes compared with no exercise. Although the definition of vigorous exercise and the magnitude of association differ among studies, our results together with previous findings support the view that vigorous-intensity exercise can reduce the risk of type 2 diabetes even when individuals engage in vigorous-intensity exercise below the recommended dose,” the researchers stated.

Further studies are needed to identify the minimum amount of vigorous-intensity exercise for T2DM prevention, they noted.

Reference: Honda T, et al. Leisure-time, occupational, and commuting physical activity and risk of type 2 diabetes in Japanese workers: a cohort study. BMC Public Health. 2015;15(1004).