Effect of IGF-1 ternary complex formation on estimates of insulin sensitivity in normal children.

BALLERINI MG; ROPELATO MG; DOMENÉ H; GUTIÉRREZ M; SCAGLIA P; BEDECARRÁS P; KARABATAS L; MARTÍNEZ A; KESELMAN A; BENGOLEA V; PIPMAN V; HEINRICH JJ; JASPER H

Viña del Mar, Chile

Congreso; XVIII Reunión Anual de la Sociedad Latinoamericana de Endocrinología Pediátrica (SLEP).; 2006

Sociedad Latinoamericana de Endocrinología Pediátrica

EFFECT OF IGF-I-TERNARY COMPLEX FORMATION (TCF) ON ESTIMATES OF INSULIN SENSITIVITY (ISES) IN NORMAL CHILDREN. Ballerini MG, Ropelato MG, Domené H, Gutiérrez M, Scaglia P, Bedecarrás P, Karabatas L, Martínez A, Keselman A, Bengolea V, Pipman V, Heinrich JJ, Jasper H. Hospitales Gutiérrez, Tornú y Fernandez. Bs. As. Argentina.Simple ISES using fasting insulin (IF) and glucose (GF) levels were proven to serve as surrogate of gold standard methods to evaluate IS in healthy children. Objectives:1) to assess GF /IF, HOMA and QUICKI indices in normal children according to Tanner (T) stage and sex; 2) to evaluate if genetics, clinical and biochemical features may affect ISES. Methods: The study involved 105 normal subjects aged 5-16 y. Insulin and GH measured by CLIA, IGF-I by RIA, IGFBP-3 by IRMA, GHR and IGFBP3 gene polymorphisms by methods in Scaglia P and TCF by methods in Gutiérrez M (this meeting). Statistical analysis by One-way ANOVA, and Pearson´s correlations. Results: No sex-related differences for ISES were found. HOMA and GF /IF were significantly different between TI and TII-V (HOMA:0.96±0.08 vs 1.42±0.1; G/I: 24.9±1.5 vs 15. 7±1.0 mg.10-4 U) . BMI, IGF-I, IGFBP3, and TCF directly correlated with HOMA (r=0.4, r=0.41, r=0.33 and r=0.6, respectively, p<0.001) and negatively with G/I (r=-0.5, r=-0.5, r=-0.4 and r=-0.65, p<0.001) and QUICKI (r=-0.31, r=-0.4, r=-0.31 and r=-0.55, p<0.01). No association was found between GHR and IGFBP3 polymorphisms or GH levels with ISES . Conclusions: The ISES calculated showed the known pubertal-associated insulin resistance compensated by increased insulin secretion. The significant correlations among BMI, IGF-I, IGFBP3 and TCF with ISES in healthy children suggests an important role for these parameters on insulin action in peripheral tissues. Further studies will be required to determine whether these effects are direct or via some other mechanism.