Aims: The prevalence of type 2 diabetes due to insulin resistance is increasing in puberty. Authors have investigated whether body weight excess arises only from increased fat content of the body. Different anthropometrical data were also analysed if they are able to predict degree of insulin resistance.
Materials and methods: 108 obese children (50 female, 58 male, Tanner st-s1-5, mean age 12.06 years, mean BMI: 30.97 kg/m2) with positive familiar anamnesis of metabolic syndrome were in the study. Bone density by PQCT as well as body composition by bioelectrical impedance analyser(inBody 3.0) were measured. Waist/hip-ratio and body fat% based on skin-fold thicknesses measurement were calculated. HOMA-index and ΣC-peptide/ΣIRI ratio (ΣC/ΣIRI) during oral glucose tolerance test as markers of insulin resistance were calculated
Results: Total Z-score of bone mineral density in obese children exceeded by 0.2 SD and trabecular density by 0.65 SD those of normal population of the same age. Obese childrens muscle mass exceeded by 6.8 kg in average compared with same values of sample population of the same age. There were slack correlations (r=0.578 vs. 0.682) between measured and calculated body fat% as well as measured fat% and BMI. There was no significant correlation between the anthropometrical values and HOMA-index, nor the ΣC/ΣIRI. Waist/hip-ratio showed a mild correlation with HOMA-index (r=0.268) and a moderate one with ΣC/ΣIRI (r=0.462).
Conclusions: Increased BMI-values in obese children are partially caused by both increased bone mineral content and higher muscle mass. BMI-values are less helpful to estimate inappropriate body composition. Differences between measured and calculated body fat% can indirectly indicate the degree of visceral fat. Increased waist/hip ratio predicts insulin resistance better. Anthropometrical data themselves do not predict insulin resistance in youngsters, it has to be determined individually. The ΣC/ΣIRI is a more exact indicator of insulin resistance than the HOMA-index.