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769. Influence of Adiposity, Physical Activity, Fitness, and Screen Time on Insulin Dynamics Over 2 Years in Children

Research Article
Mélanie Henderson, Andrea Benedetti, Tracie A. Barnett, Marie-Eve Mathieu, Johnny Deladoëy, Katherine Gray-Donald
May 2016

Commentary by Rona Macniven, GlobalPANet Executive, The University of Sydney, Australia

Rates of type 2 diabetes have increased substantially in many countries worldwide and regular physical activity is a key preventive behaviour. While this type of diabetes typically develops in middle-old age, rates of pre-diabetes indicators such as insulin sensitivity or insulin secretion have also been on the rise among children. This paper reports findings of a two year study: the Quebec Adipose and Lifestyle Investigation in Youth (QUALITY) which examined whether adiposity, fitness, moderate-to-vigorous physical activity, and screen time predict pre-diabetes indicators in children with a family history of obesity.

Children (n=630) aged 8-10 years with at least one obese parent were recruited through schools and underwent a series of tests at baseline and after two years. Fitness was measured by peak oxygen consumption, body fat percentage by dual-energy x-ray absorptiometry, moderate-to-vigorous physical activity (MVPA) through accelerometers and screen time through their self-reported average daily hours of TV, video game and computer use. The main outcomes relating to insulin were measured by the homeostatic model assessment of insulin resistance and an oral glucose tolerance test–based index. Statistical models examined the interactions between these measures

Almost 20% of the children were overweight and 22.7% obese at baseline with body fat and changes in body fat adiposity found to be the main predictors of insulin dynamics after two years. Specifically, each additional 1% of body fat decreased insulin sensitivity by 2.9% (95% CI, −3.3% to −2.5%; P < .001) and unfavourable insulin secretion responses. There were positive influences of both physical activity and screen time on these pre-diabetes indicators however, through their effects in ameliorating increases in body fat. However, MVPA levels reduced over the two years from a median of 47.7 to 39.9 minutes per day and there were increases in screen time over the same period. 

These findings suggest that while body fat is associated with the concerning development of pre-diabetes in this sample, there are also important effects derived from physical activity and sedentary behaviour. It is therefore critical to focus on developing healthy behaviours from a young age in response to the rise of type 2 diabetes. 

Source: JAMA Pediatrics OnlineFirst. Access to this article may depend on your institutional right. Full article link.