Relationship between different fasting-based insulin sensitivity indices in obese children and adolescents.

Objectives: To evaluate insulin sensitivity from data obtained from baseline values and from an oral glucose tolerance test (OGTT) in normal and obese children and adolescents.

Study Design: We recruited 89 children 4-10 years old and 82 adolescents 11-18 years old divided into moderately obese (Mod OB), severely obese (Severe OB), and non-obese (Non-OB) controls. We evaluated the relationship between four simple measures of insulin sensitivity: homeostatic model assessment (HOMA-IR), quantitative insulin sensitivity check index (QUICKI), fasting glucose to insulin ratio (FGIR), and fasting insulin resistance index (FIRI), with an insulin sensitivity measure derived from the standard 2-hour OGTT, the composite whole body insulin sensitivity index (ISI Comp).

Results: The strongest correlation was between QUICKI and ISI Comp and between FGIR and ISI Comp, (correlations [r] 0.81-0.85 in the Mod OB and 0.63-0.67 in the Severe OB). The relationship between HOMA-IR and ISI Comp and between FIRI and ISI Comp did not appear to be as strong (correlations [r] -0.36 and -0.53 in Mod OB and Severe OB, respectively). Moderately obese and severely obese children had fasting and 2-hour insulin levels 2-3 fold higher than the control group.

Conclusions: QUICKI and FGIR, are strongly correlated with OGTT measures of insulin sensitivity in children and adolescents with different degrees of obesity. These simple fasting-based indices may help the pediatrician identify patients at risk of developing insulin resistance.