Leisure-Time, Occupational, and Commuting Physical Activity and Risk of Type 2 Diabetes in Japanese Workers: A Cohort Study

Toru Honda; Keisuke Kuwahara; Tohru Nakagawa; Shuichiro Yamamoto; Takeshi Hayashi; Tetsuya Mizoue


BMC Public Health. 2015;15(1004) 

In This Article


Diabetes, an established risk factor for vascular disease,[1,2] causes macrovascular and microvascular complications.[3] The number of patients with diabetes worldwide reached 382 million in 2013[4] and is projected to keep increasing.[4] Japan is in the top 10 countries with the largest number of diabetic patients worldwide,[4] and a recent national survey[5] shows that approximately 9.5 million individuals have suspected diabetes in Japan. This metabolic disease causes an economic burden. The cost due to diabetes in Japan has been increasing and reached more than one trillion yen in 2011.[6] Physical activity has been considered to be a key strategy for the prevention of type 2 diabetes. Based on epidemiological evidence mainly on leisure-time physical activity for health, including diabetes prevention, the US government[7] and the World Health Organization[8] recommend adults engage in at least 150 min per week of moderate-intensity physical activity, 75 min per week of vigorous-intensity physical activity, or an equivalent combination of the two intensities.

Nonetheless, some important issues need to be addressed. First, a recent meta-analysis of several cohort studies[9] suggested that vigorous-intensity physical activity is associated with a greater reduction of diabetes risk compared with moderate-intensity physical activity. However, the most of the studies included in that review[10–17] were limited because individuals who engaged in moderate-intensity physical activity might also engage in vigorous-intensity physical activity and vice versa,[10–17] resulting in mixed results. Second, some studies suggested that a higher intensity of physical activity can produce greater disease risk reduction at even a low-level of physical activity above the sedentary level.[7] In a Taiwanese cohort study, vigorous-intensity exercise below the recommended dose showed a greater reduction in mortality rates than the same dose of moderate-intensity exercise.[18] Few studies,[13,16] however, examined the diabetes risk below the recommended dose and the intensity of activity. Third, data on diabetes risk are limited in relation to specific type of leisure-time activity and other domain of physical activity (i.e., occupational and commuting physical activity).[9] Finally, most data cited in the above physical activity guidelines were generated with Caucasian study participants.[7] Asian cohort studies reporting the association of physical activity with diabetes risk[19–23] have had limited assessments regarding the dose or intensity of physical activity. To overcome these issues, we examined the associations between leisure-time, occupational, and commuting physical activity and the risk of type 2 diabetes in a Japanese working population with a special emphasis on the intensity and dose for leisure-time physical activity.