Limiting sedentary time, particularly by watching no more than one hour of TV per day, may help reduce the risk of heart disease and other vascular conditions in people with a genetic predisposition to Type 2 diabetes, according to a new study published in the Journal of the American Heart Association.
- Watching two or more hours of TV daily was linked to an increased risk of heart and blood vessel diseases.
- People with a high genetic risk for Type 2 diabetes are more prone to developing cardiovascular conditions.
- Limiting TV watching to no more than one hour per day may help reduce this risk, even in those with a strong genetic predisposition.
- Individuals with a high genetic risk who watched less TV had a lower 10-year risk of atherosclerotic cardiovascular disease than those with a lower genetic risk but more TV time.
Limiting TV Time May Protect Heart Health
Limiting TV time to one hour or less per day may help reduce the risk of heart attack, stroke, and other cardiovascular diseases, even for individuals with a genetic predisposition to Type 2 diabetes. This finding comes from new research published today (March 12) in the Journal of the American Heart Association, a peer-reviewed, open-access journal.
Atherosclerotic cardiovascular disease (ASCVD) occurs when plaque builds up in the arteries, leading to conditions such as heart disease, stroke, and peripheral artery disease. These conditions can have serious consequences, including reduced quality of life, the need for surgeries like bypass procedures and stenting, amputations, and even premature death.
Exploring the Link Between TV and Type 2 Diabetes
This study is among the first to explore how genetic risk for Type 2 diabetes interacts with TV watching habits in relation to future cardiovascular disease risk.
“Type 2 diabetes and a sedentary lifestyle, including prolonged sitting, are major risk factors for atherosclerotic cardiovascular diseases. Watching TV, which accounts for more than half of daily sedentary behavior, is consistently associated with an increased risk of Type 2 diabetes and atherosclerosis. Our study provides new insights into the roles of limiting TV viewing time in the prevention of atherosclerotic cardiovascular diseases for everyone and especially in people with a high genetic predisposition for Type 2 diabetes,” said Youngwon Kim, Ph.D., lead author of the study and a professor in the School of Public Health at The University of Hong Kong in Pokfulam, Hong Kong.
Examining Data from a Large-Scale Study
This study examined data from a large biomedical database and research resource containing genetic, lifestyle, and medical records for 346,916 U.K. adults, average age of 56 years, and 45% male. During nearly 14 years of follow-up, the study identified 21,265 people who developed atherosclerotic cardiovascular disease.
For each participant, researchers calculated a polygenic risk score for Type 2 diabetes based on 138 genetic variants associated with the condition. A polygenic risk score is a statistical method to predict a person’s risk of developing a particular disease or condition by combining information from many genetic variants. To categorize participants into genotype TV-viewing groups, researchers combined three categories of Type 2 diabetes genetic risk: low, medium, and high, with two categories of participants who self-reported through questionnaires: watching TV either one hour or less a day, or two hours or more each day.
Key Findings: More TV, Higher Risk
The analysis found:
- About 21% of participants reported watching TV one hour or less a day; more than 79% reported two or more hours per day of TV-watching time.
- Compared to watching TV for one hour or less daily, spending two hours or more daily in front of the TV was associated with a 12% higher risk of atherosclerotic cardiovascular disease, regardless of their genetic risk for Type 2 diabetes.
- Evaluations indicated that participants with medium and high Type 2 diabetes genetic risk did not have a higher risk of developing atherosclerotic cardiovascular disease as long as TV viewing was limited to one hour or less daily.
- The 10-year absolute risk, or probability, of developing atherosclerotic cardiovascular disease was lower (2.13%) for people with high Type 2 diabetes genetic risk combined with one hour or less daily of TV viewing compared to people with low Type 2 diabetes genetic risk and who reported two or more hours of daily TV viewing (2.46%).
Less TV, Better Heart Health for All
“We found that people with high genetic risk for Type 2 diabetes may exhibit lower chances of developing atherosclerotic cardiovascular disease by limiting TV watching to one hour or less each day. This suggests that less TV viewing could serve as a key behavioral target for preventing atherosclerotic cardiovascular diseases linked to Type 2 diabetes genetics,” said first author of the study Mengyao Wang, Ph.D., and a recent Ph.D. graduate of The University of Hong Kong.
Public Health Strategies to Reduce Risk
“Future strategies and actions to prevent disease and improve health by reducing time in front of the TV and promoting other healthy lifestyle modifications should target broad populations, including those with a high genetic risk for Type 2 diabetes,” Wang said.
“This study shows that reducing TV watching can benefit both people at high risk for Type 2 diabetes and those at low risk. It also highlights how lifestyle choices can improve health,” said Damon L. Swift, Ph.D., FAHA, chair of the American Heart Association’s Physical Activity Committee and an associate professor at the University of Virginia in Charlottesville, Virginia. “These findings add to the evidence that sitting time may represent a potential intervention tool to improve health in people in general, and specifically for people with a high risk for Type 2 diabetes. This is especially important because people with Type 2 diabetes are at a heightened risk for cardiovascular disease compared to those who do not have diabetes.” Swift, who was not involved in this study, also noted that targeted interventions could help people who sit for long periods of time in their homes or at their workplaces.
Reference: “Genetic Susceptibility to Type 2 Diabetes, Television Viewing, and Atherosclerotic Cardiovascular Disease Risk” by Mengyao Wang, Paul James Collings, Felix R. Day, Ken K. Ong, Soren Brage, Stephen J. Sharp, Haeyoon Jang, Siyeon Suh, Shan Luo, Shiu Lun Au Yeung and Youngwon Kim, 12 March 2025, Journal of the American Heart Association.
DOI: 10.1161/JAHA.124.036811
The research involved a large group of participants who live in the U.K. and who are mostly of white British descent. The study’s findings cannot be generalized to other populations or people living in other countries.
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1 Comment
“The 10-year absolute risk, or probability, of developing atherosclerotic cardiovascular disease was lower (2.13%) for people with high Type 2 diabetes genetic risk combined with one hour or less daily of TV viewing compared to people with low Type 2 diabetes genetic risk and who reported two or more hours of daily TV viewing (2.46%).” Wow! That’s a reduction of 0.33%. A major breakthrough? No.
What do these people do when they are not watching TV? What if they sit and read a book instead? The issue seems to be sedentary behavior and not TV watching, pre se. What if they walked on a treadmill while watching, or used a stationary bike? What were they eating while watching TV? Could that have been the problem?
What a useless study.