Cardiorespiratory fitness and physical activity in youth with type 2 diabetes

Objective: The increased incidence of type 2 diabetes (T2D) among youth is hypothesized to be due, in part, to low levels of fitness and activity. Therefore, the purpose of this investigation was to examine whether cardiorespiratory fitness and physical activity are reduced in youth with T2D compared with overweight controls. Participants: Thirteen adolescent boys with previously diagnosed T2D (mean duration 2.4 +/- 1.8 yr) were matched for age and body mass index to 13 overweight, non-diabetic controls. Methods: Cardiorespiratory fitness was assessed during a progressive exercise test to volitional fatigue and physical activity was estimated from a 7-d physical activity recall. Results: Youth with T2D reported performing similar to 60% less moderate to vigorous physical activity compared with their non-diabetic counterparts (0.6 +/- 0.2 vs. 1.4 +/- 0.3 h/d, p = 0.04). Furthermore, diabetic youth exhibited significantly lower cardiorespiratory fitness levels compared with controls (28.7 +/- 1.6 vs. 34.6 +/- 2.2 mL/kg/min, p < 0.05). Conclusions: These findings support the hypothesis that cardiorespiratory fitness and physical activity are reduced in youth with T2D. Whether reduced fitness and activity contributed to the pathophysiology of the disorder cannot be determined from the cross-sectional analysis. Longitudinal studies are warranted to examine whether improvements in fitness and increased physical activity can prevent the development of T2D in high-risk youth.