A study has found that reducing sedentary time by just 30 minutes a day during adolescence and increasing exercise or sleep can lower the risk of type 2 diabetes.
According to a team led by Dr. Søren Arnois-Leblanc at Harvard Medical School on the 23rd, a five-year follow-up study tracking the daily activity patterns and health indicators of approximately 800 early-teenagers showed that reducing sedentary time by 30 minutes a day and engaging in moderate-to-high intensity physical activity (MVPA) resulted in a 15% reduction in insulin resistance.
Dr. Arnois-Leblanc stated, “Simply replacing sedentary behavior with physical activity or sleep for even a few minutes a day can have health benefits,” adding that public health strategies need to focus on reducing sedentary time and increasing exercise and sleep among adolescents. The results of this study were presented at the American Heart Association (AHA) Lifestyle Scientific Sessions 2026 (EPI) recently held in Boston.
The research team pointed out that while physical activity, sedentary time, and sleep are determinants of adolescent cardiometabolic health, there are few studies analyzing how these behaviors are interconnected within the 24-hour daily routine. They analyzed the relationship between daily lifestyle patterns during adolescence and subsequent health indicators using data from Project Viva, a long-term cohort study tracking adolescents and their mothers born in eastern Massachusetts between 1999 and 2002. 802 early adolescent participants (median age 12.9) wore wrist accelerometers and kept sleep diaries for 7 to 10 days.
Based on this data, the team calculated sleep, sedentary time, low-intensity physical activity, and the ratio of moderate to high-intensity physical activity and subsequently evaluated insulin resistance using fasting blood tests during late adolescence (median age 17.5). As a result, adolescents spent an average of 48% (11.5 hours) of their 24-hour day sitting for classes, homework, and rest; sleep accounted for 33%, low-intensity physical activity for 17%, and moderate-to-high-intensity physical activity for only 2%.
Furthermore, an analysis of health indicators from 394 individuals whose lifestyle pattern changes were confirmed revealed that those who engaged in moderate-to-high-intensity physical activity instead of sitting for 30 minutes a day showed a 14.8% decrease in insulin resistance, while those who replaced 30 minutes of sitting with sleep showed a 5% decrease. However, when the 30 minutes of sitting were replaced with low-intensity physical activity, there was no significant change in insulin resistance, and this change in activity was not associated with fasting blood glucose levels.
Dr. Harnois-Leblanc stated, “The fact that reducing sedentary time by 30 minutes and replacing it with moderate-to-high-intensity physical activity lowers insulin resistance by 15% is a significant change,” adding, “This means that changing sedentary behavior to physical activity or sleep, starting with just a few minutes a day, offers health benefits.”