Insulin sensitivity, VO2max and body composition in severely obese Swedish children and adolescents

Aim: The aim of this study was to identify relationships between insulin sensitivity (SI), cardiorespiratory fitness and body composition in severely obese Swedish children and adolescents.
Methods: Two hundred and twenty-eight obese children (119 girls, 8–16 years, body mass index (BMI) 23.2–57.0 kg/m²) performed a frequently sampled intravenous glucose tolerance test (FSIVGTT), a submaximal bicycle ergometry test and a dual-energy X-ray absorptiometry (DEXA).
Results: Mean SI (SD) was 0.38 (0.32) (×10^?5/min/pM). SI correlated positively with relative body mass (BM) VO₂max (r = 0.42) (p < 0.001), relative fat-free mass (FFM) VO₂max (r = 0.36) (p < 0.001) and negatively with body mass index standard deviation score (BMI SDS) (r =?0.22) (p = 0.001). SI did not correlate with percent body fat (r =?0.01) and absolute VO₂max (r = 0.01). In multiple regression analyses with SI as dependent variable, VO₂max and body composition, together with gender, age and Tanner stage, explained 20–26% of the variance.
Conclusion: Relative (BM) VO₂max and relative (FFM) VO₂max were stronger predictors of SI than percent body fat in severely obese children and adolescents. The study confirms that cardiorespiratory fitness is of importance for the metabolic syndrome in the studied population. Efforts to improve SI should include physical activity targeting cardiorespiratory fitness also in severely obese children and adolescents.