Physical activity and cardiorespiratory fitness in the prevention and management of type 2 diabetes in youth

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Wittmeier, Kristy Diane Marie
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Background. Estimates are that one third of children will develop type 2 diabetes in their lifetime. Lifestyle changes, including physical activity are established effective tools to prevent and manage type 2 diabetes in adults but the evidence in youth is lacking. Several key questions remain including: (1) Can youth with type 2 diabetes achieve target glycemic control with lifestyle changes alone? (2) Is type 2 diabetes in youth associated with low physical activity and cardiorespiratory fitness? and (3) What is the appropriate intensity of physical activity to reduce the risk for type 2 diabetes in overweight youth? Methods. Three studies were conducted to answer these questions: i) a retrospective chart review to determine the clinical efficacy of lifestyle monotherapy to manage glycemia in youth newly diagnosed with type 2 diabetes; ii) a cross sectional study to test the association between physical activity, cardiorespiratory fitness and type 2 diabetes risk factors in youth; and iii) a randomized controlled trial of physical activity designed to determine the training intensity required to improve insulin resistance and reduce intrahepatic lipid content in overweight youth at risk for type 2 diabetes (interim results presented). Results. Study A. Over 50% of youth newly diagnosed with type 2 diabetes and glycosylated hemoglobin ≤9% were able to achieve target glycemic control for as long as 12 months with lifestyle monotherapy. Study B. Physical activity levels (4905±2075 vs. 6937±2521 vs. 8908±2949 steps/day, p<0.05 vs. healthy weight youth) and cardiorespiratory fitness (23.4±5.9 vs. 26.7±6.0 vs. 36±6.6 ml/kg/min, ii p<0.05) are lower in youth with type 2 diabetes versus overweight and healthy weight controls. Intrahepatic lipid is significantly higher (13.0%±14.1 vs. 5.6%±6.2 vs. 1.4%±1.4, p<0.05) and inversely associated with insulin sensitivity (r = -0.40, p<0.001). Study C. Interim analyses present promising trends from a 6-month physical activity intervention. Conclusions. Lifestyle therapy can be an effective tool to manage new-onset diabetes in certain youth, and is also important in the prevention of type 2 diabetes in youth. Youth with type 2 diabetes are characterized by low levels of physical activity and cardiorespiratory fitness. Interim results are presented from a randomized controlled physical activity trial that we anticipate at completion will provide promising data to guide development of community-based programming to reduce risk for type 2 diabetes in overweight youth.
type 2 diabetes, youth, exercise, fitness, obesity, steatosis