Television viewing increases risk of type 2 diabetes, cardiovascular disease, and mortality

Abstract

Design. A meta-analysis of prospective observational studies. Subjects. The meta-analysis included eight prospective observational studies. (Four studies examined type 2 diabetes; four studies examined fatal or nonfatal cardiovascular disease [CVD]; and three studies examined all-cause mortality.) The four studies addressing type 2 diabetes included 175,938 participants; the four studies examining fatal or nonfatal CVD had a total of 34,253 participants; and the three studies that examined all-cause mortality included 26,509 participants. Mean follow-up duration was 8.5 years for studies examining type 2 diabetes, 10 years for those examining fatal or nonfatal CVD, and 7 years for those addressing all-cause mortality. Each of the study populations was healthy at baseline.Methods. The goal of the meta-analysis was to determine the association between TV viewing and the risk of type 2 diabetes, fatal or nonfatal CVD, and all-cause mortality. Random effects models were used to pool relative risk (RR) estimates, and heterogeneity among studies was examined by I2 statistics. Sensitivity analyses evaluated whether meta-analysis results could have been affected by a single study.Results. The pooled RR of developing type 2 diabetes per every 2 hours of TV watching per day was 1.20 (95% CI 1.14-1.27). The risk of fatal or nonfatal cardiovascular events was 1.15 (95% CI 1.05-1.23), and risk for all-cause mortality was 1.13 (95% CI 1.07-1.18). Risk of all-cause mortality appeared to increase at a threshold of > 3 hours of television watching per day, but both type 2 diabetes and CVD had linear increases in risk with each additional 2 hours per day of TV watching. Data were not available to fully assess the degree to which dietary intake and physical inactivity explain the negative effects of TV viewing on outcomes.Conclusion. TV viewing was associated with increased risk of type 2 diabetes, cardiovascular events, and all-cause mortality in a dose-dependent manner.