Type 2 diabetes in youth: Are more physical activity and less screen time the answer?
Prediabetes and type 2 diabetes are on the rise in young people, so finding ways to prevent them early in life is becoming ever more urgent. Delegates at the American Diabetes Association 81st Scientific Sessions were treated to a closer examination of the competing impacts of physical activity and screen time on type 2 diabetes in youth.
Soren Harnois-Leblanc, a PhD candidate at Université de Montréal discussed her team’s work in this area in her presentation: Exploring the association between physical activity levels and sedentary behaviours with risk of type 2 diabetes from childhood to adolescence – A causal inference analysis.
Research has shown that lifestyle ‘habits-based’ interventions can delay or prevent transition from prediabetes to type 2 diabetes in adults. When it comes to children, she said, randomised controlled trials of physical activity interventions in those living with overweight or obesity have shown reduced fasting insulin levels, improved insulin sensitivity, and a few showed lowered 2-hour post-load glucose levels. However, these trials were of limited duration and generalisability.
Associations have been found between physical activity, sedentary behaviours and insulin sensitivity and secretion in paediatric cohort studies, but Soren highlighted the many confounders - such as calorie intake, adiposity, etc. Therefore, the long-term prevention potential of physical activity and low sedentary behaviour on type 2 diabetes risk in children is unclear.
Her team’s research objectives were to estimate causal effects of physical activity levels and sedentary behaviours from childhood to late adolescence on insulin sensitivity, insulin secretion and dysglycaemia (fasting and 2-hour post-load glucose levels) in late adolescence.
She and her colleagues analysed data from the Quebec Adipose and Lifestyle Investigation in Youth Cohort, which was conducted in children with one or both parents with obesity, and all were White Canadian. There were three evaluation cycles at 8-10 years, 10-12 years and 15-17 years.
Exposures and outcomes were measured each time: exposures were moderate-to-vigorous physical activity (MVPA) and sedentary time assessed by 7-day accelerometry, and usual leisure screen time by questionnaire; outcomes were measured with an oral glucose tolerance test to assess insulin sensitivity, insulin secretion (first phase 0-30 minutes and second phase 0-120 minutes), and fasting and 2-hour plasma glucose.
Confounding variables were measured at every cycle. They included age, sex, family history of diabetes, body fat percentage, diet quality, energy intake and cardiorespiratory fitness.
Her first eye-opening slide showed the decline in physical activity in both boys and girls that happened during adolescence, along with an increase in sedentary time.
When it came to the average treatment effects of MVPA, sedentary behaviours and screen time, they observed that if all the children did 10 minutes more daily physical activity, they would have had a 5% lower second-phase insulin secretory requirement (adjusted for insulin sensitivity). They also found that physical activity increased insulin sensitivity and decreased first-phase insulin secretion requirement.
With regard to screen time, they found that if all the children had one hour more of screen time per day, they would present with 9% lower insulin sensitivity, and their insulin secretory requirement would be 7% higher in the first phase and 6.5% higher in the second.
With the fasting glucose and 2-hour post-load glucose, there was a deleterious effect for screen time on fasting glucose but it wasn’t clinically meaningful. However, they did note a modest effect of sedentary behaviour on 2-hour glucose.
The analysis had strengths, such as extensive measurement of confounders, as well as limitations such as generalisability to other ethnic groups.
In conclusion, she said, promoting physical activity and lowering sedentary behaviours during childhood and adolescence improves insulin sensitivity and reduces insulin secretion (and possibly 2-hour post-load glucose levels) in late adolescence. All of this could contribute to the prevention of prediabetes and type 2 diabetes among White Canadian children with parental obesity.
Watch out for our new course on lifestyle interventions, coming next year.
The opinions expressed in this article are those of the author, Dr Eleanor D Kennedy.