Adolescents who replace just 30 minutes of sedentary behavior each day, such as sitting on the couch or spending time at a computer, with moderate to vigorous physical activity and sleep may reduce insulin resistance, a key factor in preventing the development of type 2 diabetes, according to a preliminary study presented at the American Heart Association’s EPI|Lifestyle Science Session 2026. The conference will be held in Boston from March 17-20, 2026 and will provide the latest information. Epidemiological science of prevention, lifestyle, and cardiometabolic health.
“We were pleasantly surprised by the strength of the association between replacing 30 minutes of sedentary time with moderate-to-vigorous physical activity. A 15% reduction in insulin resistance is a pretty significant change,” said the study’s lead author Soren Harnois-Leblanc, RD, a postdoctoral fellow in the Harvard Pilgrim Healthcare Institute and the Division of Population Medicine at Harvard Medical School. “Our findings mean that replacing sedentary behavior with moderate to vigorous physical activity and sleep, even for just a few minutes per day, can have health benefits.”
To assess the impact of typical daily activities on the development of insulin resistance in teens, researchers looked at health data from Project Viva, an ongoing health study of children and their mothers born between 1999 and 2002. Insulin resistance was measured using Homeostasis Model Assessment of Insulin Resistance (HOMA-IR), a test that estimates insulin resistance based on fasting blood glucose and insulin levels. In early adolescence, at an average age of nearly 13 years, 802 participants took sleep records and wore accelerometers (sensors that quantify the acceleration of movement that allow researchers to derive the intensity and duration of physical activity) continuously for seven to 10 days, providing a breakdown of the physical activity they participated in over a typical 24-hour period.
So far, the highest percentage of the day was spent in sedentary activities, at 48%, or 11.5 hours per day. Examples of sedentary time often include sitting in class, doing homework, commuting, and evening breaks when using electronic devices or watching TV.
Other daily activities reported over a 24-hour period included sleeping (33%), low-intensity physical activity (e.g., casual walking, 17%), and moderate-to-vigorous physical activity (e.g., running, swimming, basketball, 2%).
The researchers then calculated how much shifting from sedentary activity to different types of physical activity and sleep for just 30 minutes affected the estimated insulin resistance levels of the 394 study participants.
Research findings include:
- Adolescents who replace 30 minutes of sedentary time with moderate-to-vigorous physical activity can reduce their measure of insulin resistance, or HOMA IR score, by nearly 15%.
- Participants who traded 30 minutes of sedentary time for sleep were able to reduce their insulin resistance by nearly 5%.
- Replacing 30 minutes of sitting with low-intensity physical activity did not significantly change insulin resistance levels.
- Activity composition was associated with insulin resistance, but not with levels of adiponectin (a hormone produced by fat cells) or fasting blood sugar levels (measurements used to diagnose prediabetes and type 2 diabetes).
This study shows that young people spend much of their day sedentary and spend only a small amount of time physically active. Interestingly, teens who had moderate to vigorous physical activity during early adolescence showed signs of decreased insulin resistance later in life. The big takeaway is that being active early in life can make a huge difference to your long-term health. ”
Dr. Kershaw Patel, American Heart Association volunteer and chair-elect of the association’s Council on Epidemiology and Prevention
Patel, who was not involved in the study, is an assistant professor of cardiology at the DeBakey Heart and Vascular Institute at Houston Methodist Hospital in Houston.
The American Heart Association’s Life’s Essential 8 Metrics for Optimal Cardiovascular Health includes strategies for incorporating a healthy lifestyle into your daily life. For example, dimming the lights before bed, creating a nighttime routine without screened electronic devices, and setting your phone to “do not disturb” mode (or leaving it outside your bedroom while you sleep) can help improve the quality and quantity of your sleep. Integrating physical activity with social time with friends to clear your mind and reduce stress can make hiking and other forms of exercise more appealing than sedentary activities.
Although the study found no association between increased time spent in light physical activity and decreased insulin resistance, the researchers urge additional research on the topic.
“Spending more time in light physical activity may be beneficial in preventing cardiometabolic diseases in adults. Light physical activity is an interesting goal because it is likely to be easy to incorporate into daily life,” said Arnois-Leblanc.
The current study had several limitations, including that insulin resistance information in late adolescence was available for only 49% of participants with accelerometer data collected in early adolescence. Additionally, a causal relationship between daily activity and insulin resistance cannot be proven with this data analysis.
Research details, background and design:
- The study included health information for 802 participants ages 12 to 17 who were born in eastern Massachusetts between 1999 and 2002 and enrolled in Project Viva, an ongoing study aimed at improving the health of children and their mothers.
- Fifty-two percent of participants were female, 64% self-identified as non-Hispanic white, 15% self-identified as non-Hispanic black, and 9% self-identified as Hispanic.
- Participants, who were early adolescents (median age 12.9 years), wore accelerometers on their wrists and completed sleep logs for 7 to 10 consecutive days. This allowed researchers to calculate the average number of minutes spent sleeping, sitting, light physical activity, and moderate to vigorous physical activity every 24 hours.
- During late adolescence (median age 17.5 years), 394 participants with accelerometer data underwent fasting blood concentration tests to measure levels of adiponectin (a hormone produced by fat cells), glucose (sugar), and insulin. Fasting blood glucose and fasting insulin levels were used to calculate HOMA-IR, a measure of insulin resistance that signals the risk of progressing to type 2 diabetes.
- The researchers used a statistical method called compositional data analysis to examine the distribution of four types of physical activity over a 24-hour period. They then used the model to estimate how a 30-minute substitution of one behavior for another would affect test results from adolescence onwards. Results were adjusted for age, gender, season in which participants wore the accelerometer, mother’s education level, and household income.
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