TABLE 1

Spearman correlation coefficients between surrogate indexes of β-cell function and insulin release during the first phase (0–10 min) and second phase (10–60 min) and total (0–60 min) during an IVGTT

β-Cell function indexes	Insulin release during an IVGTT
β-Cell function indexes	First phase	Second phase	Total
HOMA-β	0.568	0.645	0.663
Insulinogenic index	0.579	0.469	0.541
InsAUC₃₀/GluAUC₃₀	0.666	0.707	0.743
ΔInsAUC₁₂₀/ΔGluAUC₁₂₀	0.375	0.409	0.405
InsAUC₁₂₀/GluAUC₁₂₀	0.648	0.750	0.775
First-phase Stumvoll	0.651	0.663	0.702
Second-phase Stumvoll	0.662	0.692	0.730
Fasting insulin	0.548	0.747	0.735
Insulin at 30 min of an OGTT	0.615	0.691	0.715
Insulin at 120 min of an OGTT	0.429	0.673	0.645
Insulin AUC during an OGTT	0.558	0.770	0.776

P < 0.001 for all correlation coefficients. Indexes of β-cell function were calculated as described previously: HOMA-β(30), insulinogenic index (31), ΔInsAUC₁₂₀/ΔGluAUC₁₂₀ (25), InsAUC₁₂₀/GluAUC₁₂₀ (31), first phase Stumvoll (32), and second phase Stumvoll (32). InsAUC₃₀/GluAUC₃₀ = (insulin at 0 min + insulin at 30 min of an OGTT)/(glucose at 0 min + glucose at 30 min of an OGTT).