Indexes of insulin resistance using the oral glucose tolerance test (O-GTT) in Japanese children and adolescents

Abstract

An oral glucose tolerance test (O-GTT) was conducted in 96 non-obese healthy children (7 to approximately 11 years old) and adolescents (12 to approximately 16 years old) to obtain the index of insulin resistance from the insulin (IRI) and C-peptide (CPR) values of fasting. 2-hour postload conditions and the sigma values, and the homeostasis model assessment ratio (HOMA-R) by assuming the value of the mean + 2SD to be the upper limit of the normal value for each clinical variable. The results show that the adolescents, whose insulin resistance is thought to increase, showed higher IRI and CPR values of the 2-hour postload condition and sigma values compared to those of the children, but there were no differences between the 2 age groups in the values of the fasting condition, as well as in the HOMA-R values which were calculated from the fasting values. These findings indicate that there is a limitation in using fasting values to judge insulin resistance. Instead, using the 2-hour postload values and/or the sigma values is more appropriate.