Measurement of Insulin Sensitivity in Children: Comparison Between the Euglycemic Hyperinsulinemic Clamp and Surrogate Measures

Abstract

Objective: This study compared fasting insulin and measures of insulin sensitivity based on fasting insulin and glucose (i.e., HOMA, QUICKI, FGIR) or triglycerides to the insulin clamp in a cohort of children/adolescents.

Research Design and Methods: The subjects were Minneapolis 5^th-8^th grade students. Euglycemic hyperinsulinemic clamps were performed on 323 at mean age 13 and repeated on 300 at mean age 15. Insulin sensitivity (M) was determined by glucose uptake (mg/kg/min) adjusted for lean body mass (M_LBM) and steady state insulin (M_LBM/ln SSI). Comparisons were made for the whole cohort and by body size (BMI <85%ile vs. BMI ≥85%ile). ROC curves tested whether specific fasting insulin cut-points separated true positive from false positive approximations of insulin resistance.

Results: Fasting insulin was significantly correlated with HOMA (r=0.99), QUICKI (r=0.79), FGIR (r=-0.62) and [ln fasting insulin + ln triglycerides] (0.88). Correlations of the surrogates with M_LBM were significantly lower than M for the total cohort and ≥85%ile group. In general, correlations in the ≥85%ile group were higher than the <85%ile group. Correlations with M_LBM and M_LBM/ln SSI decreased in the total cohort and ≥85%ile group from age 13 to 15. ROC curves showed only a modest capability to separate true from false positive.

Conclusions: Surrogate measures are only modestly correlated with the clamp measures of insulin sensitivity and do not offer any advantage over fasting insulin. In general, lower correlations are seen with M_LBM than M and with heavier than thin individuals.