Replacing Sedentary Time with Physical Activity or Sleep May Reduce Type 2 Diabetes Risk in Adolescents

Adolescents who replaced just 30 minutes of sedentary behaviors each day with moderate-to-vigorous physical activity or sleep may lower their insulin resistance, a key factor in preventing the development of Type 2 diabetes, according to preliminary research presented at the American Heart Association's EPI|Lifestyle Scientific Sessions 2026. The analysis of health data from Project Viva, a long-term study of the health of women and children in Eastern Massachusetts, suggests that public health initiatives to promote physical activity or sleep rather than sedentary activities could help preserve cardiometabolic health among teens in the U.S.

"I was happily surprised with the strength of the association of replacing 30 minutes of sedentary time with moderate-to-vigorous physical activity - a 15% lower insulin resistance is quite a big change," said Soren Harnois-Leblanc, Ph.D., R.D., lead author of the study and a postdoctoral researcher in the department of population medicine at the Harvard Pilgrim Health Care Institute and Harvard Medical School. "Our findings mean that switching from sedentary behaviors to moderate-to-vigorous physical activity or sleep, even if it is only a few minutes per day to start, was beneficial for health."

To assess the impact of typical daily activities on insulin resistance development in teenagers, investigators examined health data from 802 participants in early adolescence who kept sleep logs and wore accelerometers for 7-10 days. The highest percentage of daily time, 48% or 11.5 hours per day, was spent in sedentary activities like sitting in class, doing homework, commuting, and screen time. Other daily activities included sleep (33%), low-intensity physical activity (17%), and moderate-vigorous physical activity (2%).

Researchers calculated how much a shift of just 30 minutes from sedentary activity to various types of physical activity or sleep could have impacted estimated insulin resistance levels in 394 participants. Adolescents who replaced 30 minutes of sedentary time with moderate-vigorous physical activity could lower their HOMA-IR score, a measurement of insulin resistance, by nearly 15%. Participants who exchanged 30 minutes of sedentary time with sleep could lower insulin resistance by nearly 5%. Shifting 30 minutes of sedentary time to low-intensity physical activity did not have a significant change in insulin resistance levels.

"This study shows that young adolescents spend a lot of their day being sedentary and only a small amount of time being physically active," said Kershaw Patel, M.D., an American Heart Association volunteer and chair elect of the Association's Council on Epidemiology and Prevention. "Interestingly, teens who had more moderate to vigorous physical activity early in adolescence showed signs of lower insulin resistance later on. The big takeaway is being active early in life can really make a difference for long-term health."

The American Heart Association's Life's Essential 8 metrics for optimal cardiovascular health include strategies for incorporating healthy lifestyle into daily life. While the study did not find an association between more time spent in light physical activity and lower insulin resistance, investigators urge additional research on this topic. "More time spent in light physical activity may be beneficial to prevent cardiometabolic disease in adults. Light physical activity is an interesting target because it is likely easier to integrate into everyday routines," said Harnois-Leblanc.

The study had limitations, including that insulin resistance information in late adolescence was available for only 49% of participants who had accelerometer data collected in early adolescence. Additionally, cause-and-effect for daily activities and insulin resistance cannot be proven by this data analysis. The study featured in this news release is a research abstract, and abstracts presented at the American Heart Association's scientific meetings are not peer-reviewed, with findings considered preliminary until published as a full manuscript in a peer-reviewed scientific journal.