How much of an effect does sedentary behavior have on glucose metabolism status and metabolic syndrome?
Too much sedentary behavior may play a significant role in the development of type 2 diabetes mellitus (DM), according to a new study.
Sedentary behavior, such as watching TV or using the computer, can be objectively measured using an accelerometer. A number of accelerometry studies have shown unfavorable associations between total amount of sedentary time and metabolic health outcomes, including waist circumference, cholesterol and triacylglycerol levels, markers of insulin resistance, and the metabolic syndrome, noted the researchers, led by Julianne van der Berg, a PhD candidate in social medicine at Maastricht University, the Netherlands.
In a few studies, more sedentary breaks have been associated with better metabolic health.
The researchers measured the total amount and patterns of sedentary behavior with an accelerometer, measuring both breaks (how often sedentary time is interrupted) and sedentary bouts (the length of uninterrupted sitting time).
The study used the thigh-worn activPAL3 accelerometer, which classifies sedentary behavior using data on posture. This data has been shown to be an accurate means of assessing sedentary behavior.
The aim of this observational, prospective, population-based cohort study was to examine associations of total amount and patterns of sedentary behavior with glucose metabolism status and metabolic syndrome among the 2497 participants, mean age 60 years.
To determine glucose metabolism status, participants underwent an oral glucose tolerance test.
Overall, 1395 (55.9%) participants had normal glucose metabolism, 388 (15.5%) participants had impaired glucose metabolism, and 714 (28.6%) participants had type 2 DM.
The results showed that participants with type 2 DM had the most sedentary time, up to 26 minutes more per day compared with participants with impaired glucose metabolism or normal glucose metabolism, the researchers stated.
After adjustment for 11 factors potentially linked to metabolic dysfunction, including high-intensity physical activity and body mass index, “the results showed that each extra hour of sedentary time raised the risk of type 2 DM by 22% and of 39% for the metabolic syndrome,” they stated.
The pattern of sedentary time – the number of breaks, prolonged sedentary bouts defined as 30 or more minutes, and average bout duration -- showed no significant association with either glucose metabolism status or risk of metabolic syndrome.
"To our knowledge, our study is the largest in which posture-discriminating accelerometry was used to objectively measure total amount and patterns of sedentary behavior in a sample of adults comprising participants with type 2 diabetes or impaired or normal glucose metabolism," stated the researchers.
They noted that it may be possible that participants with type 2 DM had more sedentary time because of their poorer health. However, after excluding participants on insulin, who may have more severe disease and worse health, the results did not change.
Also, sedentary behavior was only measured during 1 week, and this may not reflect true habits.
The researchers concluded that reducing the total amount of time spent sitting each day could bring health benefits. They suggested that clinicians should consider including strategies to reduce the amount of sedentary time in diabetes prevention programs.
Reference: van der Berg JD, et al. Associations of total amount and patterns of sedentary behaviour with type 2 diabetes and the metabolic syndrome: The Maastricht Study. Diabetologia. Epub 2016 Feb 2.