Research Highlights:
- A sedentary lifestyle such as watching TV (two or more hours daily) may be a key factor in the risk of developing heart and blood vessel diseases, according to an analysis of health records from a large U.K. biomedical database.
- People with higher genetic risk for Type 2 diabetes may be more likely to have a heart attack, stroke or other types of atherosclerotic cardiovascular disease. However, limiting TV watching to no more than one hour a day may help offset the increased risk of these atherosclerotic events associated with a high genetic risk of Type 2 diabetes.
- People who had high Type 2 diabetes genetic risk but who reported one hour or less daily of TV viewing had a relatively lower risk of developing atherosclerotic cardiovascular disease within the next 10 years compared with people who had low Type 2 diabetes genetic risk but reported two or more hours of daily TV viewing.
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DALLAS, March 12, 2025 — Watching no more than one hour of TV a day may lower the risk of heart attack, stroke and other blood vessel diseases among people with varying levels of genetic risk for Type 2 diabetes, including high genetic risk, according to new research published today in the Journal of the American Heart Association , an open access, peer-reviewed journal of the American Heart Association.
Atherosclerotic cardiovascular disease , or ASCVD, is caused by plaque buildup in arterial walls and refers to conditions that include heart disease, stroke and peripheral artery disease . These conditions may lead to severe consequences, such as compromised quality of life, bypass surgeries, stenting procedures, amputations and premature death.
This study is one of the first to examine how the genetic risk for Type 2 diabetes may interact with TV viewing in relation to the future risk of atherosclerotic cardiovascular disease.
"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.
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.
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%).
"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.
"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.
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.
Co-authors, disclosures and funding sources are listed in the manuscript.
