According to preliminary research presented at the American Heart Association’s EPI|Lifestyle Scientific Sessions 2026, teens who replaced half an hour of sedentary behavior, such as sitting on the couch or spending time at a computer, with moderate to vigorous physical activity or sleep each day may reduce their insulin resistance, a key factor in preventing the development of type 2 diabetes. The meeting is in Boston March 17-20, 2026 and offers the latest. Epidemiological science on prevention, lifestyle and cardiometabolic health.
“I was surprised by the power of replacing 30 minutes of sedentary time with moderate to vigorous physical activity — 15% less insulin resistance is quite a big change,” said Soren Harnois-LeBlanc, PhD, RD, a postdoctoral researcher in the department of population medicine at Harvard Pilgrim Health Care Institute and Harvard Medical School, both in Boston, and lead author of the study. “Our findings imply that switching from sedentary behavior to moderate-to-vigorous physical activity or sleep, even if it was just a few minutes per day to begin with, was beneficial for health.”
To assess the impact of normal daily activities on the development of insulin resistance in adolescents, 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 the 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 about 13 years of age on average, 802 participants kept sleep logs and wore an accelerometer (a sensor that measures the speed of movement, allowing researchers to obtain the intensity and duration of physical activity) for 7–10 consecutive days, providing details of the activity levels 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, evening commutes, and free time, which often comes with screen time on electronic devices 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 just a 30-minute change from sedentary activity to different types of physical activity or sleep could affect predicted insulin resistance levels in 394 of the study participants.
Among the study’s findings:
- Adolescents who replaced 30 minutes of sedentary time with moderate-vigorous physical activity could reduce measures of insulin resistance, or reduce their HOMA IR scores by about 15%;
- Participants who swapped 30 minutes of sedentary time with sleep could reduce insulin resistance by about 5%;
- Replacing 30 minutes of sedentary time with low-intensity physical activity did not cause any significant change in insulin resistance levels.
- While the activity structure 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 most of their day being sedentary and only a small amount of time being physically active. Interestingly, adolescents who did more moderate to vigorous physical activity in early adolescence showed less symptoms of insulin resistance later on. The big lesson is that being active early in life can really make a difference in long-term health.”
Kershaw Patel, MD, an 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 essential 8 metrics of life for optimal heart health include strategies for incorporating a healthy lifestyle into daily life. For example, dimming the lights before bed, creating a nighttime routine that doesn’t involve electronic devices with screens, and putting the phone on “do not disturb” (or leaving it outside the bedroom while you sleep) can help improve the quality and quantity of sleep. Integrating physical activities with social time with friends to clear your mind or reduce stress can make hiking or other exercise more appealing than sedentary activities.
Although the study found no association between spending more time in light physical activity and less insulin resistance, the investigators have urged additional research on this topic.
“Spending more time in light physical activity may be beneficial for preventing cardiometabolic disease in adults. Light physical activity is an interesting target because it is easy to incorporate into everyday routines,” Harnois-LeBlanc said.
The current study had some limitations, including that information on insulin resistance in late adolescence was only available for 49% of participants who had accelerometer data collected in early adolescence. Additionally, the cause and effect of daily activities and insulin resistance cannot be proven from this data analysis.
Study description, background and design:
- The study included health information from 802 participants aged 12–17, who were born in Eastern Massachusetts between 1999–2002, 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% self-identified as non-Hispanic white, 15% self-identified as non-Hispanic black, and 9% self-identified as Hispanic.
- Participants in early adolescence (mean age 12.9 years) wore wrist accelerometers for 7–10 consecutive days and completed sleep logs, allowing researchers to calculate the average number of minutes spent sleeping versus sedentary time versus light physical activity versus moderate to vigorous physical activity in each 24-hour period.
- In late adolescence (average age of 17.5 years), 394 participants with accelerometer data had fasting blood level tests collected to measure adiponectin (a hormone produced by fat cells), glucose (sugar) and insulin levels. Fasting glucose and fasting insulin levels were used to calculate HOMA-IR, a measure of insulin resistance that informs the risk of developing type 2 diabetes.
- The investigators used a statistical method called compositional data analysis to examine the distribution of 4 types of physical activity within a 24-hour period. They then used modeling to predict how substituting 30 minutes from one behavior for another might affect test results in later adolescence. The results were adjusted for age, gender, the season in which participants wore the accelerometer, the mother’s educational level, and family income.
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