Research Highlights:
- If adolescents replaced 30 minutes of sedentary time each day with sleep or moderate-to-vigorous physical activity, it may reduce their insulin resistance and thus reduce their risk of developing Type 2 diabetes, according to an analysis of health data from Project Viva, a long-term study of the health of women and children in Eastern Massachusetts.
- Substituting 30 minutes per day of sedentary time with moderate-to-vigorous physical activity reduced a measurement of insulin resistance by nearly 15%.
- Public health initiatives to promote physical activity or sleep rather than sedentary activities could help preserve cardiometabolic health among teens in the U.S.
- Note: The study featured in this news release is a research abstract. Abstracts presented at the American Heart Association's scientific meetings are not peer-reviewed, and the findings are considered preliminary until published as a full manuscript in a peer-reviewed scientific journal.
Embargoed until 1:30 p.m. ET/12:30 p.m. CT, Friday, March 20, 2026
Boston, March 20, 2026 — Adolescents who replaced just half an hour of sedentary behaviors, such as sitting on the couch or spending time at the computer, each day for 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 meeting is in Boston, March 17-20, 2026, and offers the latest epidemiological science on prevention, lifestyle and cardiometabolic health.
"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, both in Boston. "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 the development of insulin resistance in teenagers, investigators examined health data from Project Viva, an ongoing health study of children born between 1999-2002 and their mothers. Insulin resistance was measured using Homeostatic Model Assessment for Insulin Resistance (HOMA-IR), a test that estimates insulin resistance based on fasting blood glucose and insulin levels. In early adolescence, at an average of nearly 13 years old, 802 participants kept sleep logs and wore an accelerometer (a sensor that quantifies movement accelerations, from which researchers can derive the intensity and duration of physical activity) constantly for 7-10 days, providing a breakdown of the movement activities they engaged in over a typical 24 hours.
By far, the highest percentage of daily time, 48% or 11.5 hours per day, was spent in sedentary activities. Examples of sedentary time may include sitting in class, doing homework, commuting and downtime in the evening, which often comes with screen time on an electronic device or watching TV.
Other daily activities, reported over a 24-hour period, included sleep (33%), low-intensity physical activity (such as casual walking, 17%), and moderate-vigorous physical activity (such as running, swimming or playing basketball, 2%).
The researchers then 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 of the study participants.
Among the study findings:
- Adolescents who replaced 30 minutes of sedentary time with moderate-vigorous physical activity could lower a measurement of insulin resistance, or lowering their HOMA IR score, 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.
- While activity composition was associated with insulin resistance, it was not associated with levels of adiponectin (a hormone produced by fat cells) or fasting glucose levels (a measure used to diagnose prediabetes and Type 2 diabetes).
"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." Patel, who was not involved in this study, is an assistant professor of cardiology at Houston Methodist Hospital's DeBakey Heart & Vascular Institute in Houston.
The American Heart Association's Life's Essential 8 metrics for optimal cardiovascular health includes strategies for incorporating healthy lifestyle into daily life. For example, dimming lights before bedtime, creating a nighttime routine that doesn't include electronic devices with screens and putting the phone on "do not disturb" (or leaving it outside the bedroom while sleeping) can help to improve quality and quantity of sleep. Integrating physical activities with social time with friends, to clear your mind or reduce stress can make hikes or other exercise more appealing than sedentary activities.
While the study did not find an association between more time spent in light physical activity and lower insulin resistance, the 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 current study had some 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.
Study details, background and design:
- The study included health information for 802 participants, ages 12-17, who were born between 1999-2002 in Eastern Massachusetts, and who were enrolled in Project Viva, an ongoing study aimed at improving the health of children and their mothers.
- 52% of participants were female, 64% were self-identified as non-Hispanic white, 15% self-identified as non-Hispanic Black and 9% self-identified as Hispanic.
- Participants in early adolescence (median age of 12.9 years) wore a wrist accelerometer for 7-10 consecutive days and completed sleep logs, allowing researchers to calculate the average number of minutes in each 24-hour period were spent sleeping vs. sedentary time vs. light physical activity vs. moderate to vigorous physical activity.
- In late adolescence (median age of 17.5 years), 394 participants with accelerometer data had fasting blood level tests collected to measure levels of adiponectin (a hormone produced by fat cells), glucose (sugar) and insulin. Fasting glucose and fasting insulin levels were used to calculate HOMA-IR, a measure of insulin resistance that informs on the risk of progressing to Type 2 diabetes.
- Investigators used a statistical method called compositional data analysis to examine the distribution of 4 types of physical activities within a 24-hour period. They then used modeling to estimate how 30-minute substitutions from one behavior to another could affect test results in later adolescence. Results were adjusted for age, sex, the season in which the participants wore the accelerometer, mother's educational level and family income.
Co-authors, disclosures and funding sources are listed in the abstract.
Statements and conclusions of studies that are presented at the American Heart Association/American Stroke Association's scientific meetings are solely those of the study authors and do not necessarily reflect the Association's policy or position. The Association makes no representation or guarantee as to their accuracy or reliability. Abstracts presented at the Association's scientific meetings are not peer-reviewed, rather, they are curated by independent review panels and are considered based on the potential to add to the diversity of scientific issues and views discussed at the meeting. The findings are considered preliminary until published as a full manuscript in a peer-reviewed scientific journal.
