[Glucose and insulin concentrations during oral glucose tolerance test in healthy children--application of insulin resistance index according to Belfiore in the developmental age].

Introduction: Sensitivity to insulin changes during puberty. It is necessary to distinguish physiological insulin resistance (IR) from pathological one. In children the IR index proposed by Belfiore (IRI(Belfiore)) could be used. Application of this formula is possible, when the reference values of the area under curve of glucose (GLU(AUC)) and insulin (INS(AUC)) concentration during oral glucose tolerance test (OGTT) are available for the studied population. Derivation of such reference values was the goal of this study.

Material and methods: Forty healthy children, aged 8-18.2 years, were enrolled in the study. Regarding the stages of puberty, the children were divided into 3 groups: A--stage I, B--stage II or III and C--stage IV or V. Serum glucose and insulin concentrations were measured for each child during OGTT and GLU(AUC) and INS(AUC) were calculated. The obtained mean values of GLU(AUC) and INS(AUC) for each group were used to calculate IRIBelfiore. To determine the cut-off point between physiological and pathological IR, receiver operating characteristic (ROC) analysis was performed for 40 studied children and 50 obese and insulin resistant children (according to QUICKY and/or elevated insulin concentration during OGTT), matched for age, sex and stages of puberty with the study group.

Results: The following mean values of GLU(AUC) and INS(AUC) were obtained in particular groups: A--189.3 mg/dL and 37.1 ulU/mL; B--207.4 mg/dL and 54.5 ulU/mL; C--188.8 mg/dL and 59.4 ulU/mL, respectively. The cut-off point value between physiological and pathological IR at the level 1.27 for IRI Belfiore was calculated.

Conclusions: 1. The mean values of GLU(AUC) and INS(AUC) obtained during OGTT could be used to calculate IRI Belfiore in children. 2. IRI(Belfiore) values above 1.27 indicate pathological IR in developmental age.