News & Research

Television viewing and risk of type 2 diabetes, cardiovascular disease, and all-cause mortality: a meta-analysis, by Anders Grøntved and Frank B. Hu. JAMA 305;2448–2455, 2011

What is the problem and what is known about it so far?

Television watching is reported to be the most popular daily non-physical free time activity in the modern world. TV watching has been linked to the rise of type 2 diabetes and heart and blood vessel disease (also known as cardiovascular disease or CVD), and also a rise in rates of death from all causes. It promotes unhealthy behaviors such as inactivity, unhealthy eating, and smoking, which are directly associated with developing type 2 diabetes, CVD, or other major health problems.

Why did the researchers do this particular study?

The researchers did this study because there was not a complete and detailed analysis of all the current studies looking at the time spent watching television and the possible connection to health-related problems.

Who was studied?

The researchers looked at 1,655 studies related to the lack of physical activity, long television watching, and health problems. In the final analysis, they used 4 studies reporting on type 2 diabetes , 4 reporting on CVD, and 3 reporting on related health problems. Of these 10 studies, 8 were fully reviewed in the final analysis.

How was the study done?

The researchers did an Internet search for studies using several related key words, including "TV" or "television" or "screen time" and "diabetes" or "cardiovascular," "coronary," "stroke," "mortality," and "death." They also reviewed the reference lists of all the published studies for additional studies not found not in their initial search. The researchers then collected the results from each of the studies in order to compare and contrast the findings.

What did the researchers find?

The researchers found that the longer people sat and watched television, the greater the risk of developing type 2 diabetes, CVD, and other health problems. The researchers estimated that there were 38 cases of fatal heart disease, 176 cases of type 2 diabetes, and 104 cases of other major health concerns per 1,000 individuals per year for every 2 hours of television watching per day in the U.S.

What were the limitations of the study?

The total number of studies looked at was small, and the details from study to study were different. Not all of the studies measured actual physical activity, and some study results could have been misclassified during the analysis. Also, the time spent watching television was self-reported from memory and may not have been exact.

What are the implications of the study?

The number of hours spent watching television is consistently tied to a higher risk of developing type 2 diabetes, CVD, and other major health problems. Additional study is needed to see if reducing the time in front of the television can prevent disease and death.

For More Information

Check Up America: Lower Your Risk for Type 2 Diabetes and Heart Disease

Physical Activity and Diabetes

The "I Hate to Exercise" Book for People with Diabetes