Clinical Evaluation of Endogenous Insulin Secretion via Sulfonylurea Receptor and Insulin Sensitivity Estimated by the Nateglinide Administration Test in Type 2 Diabetics

Abstract

We attempted to estimate endogenous insulin secretion via sulfonylurea receptor and insulin sensitivity to endogenous insulin simultaneously using the nateglinide administration test. The levels of plasma glucose and serum immunoreactive insulin (IRI) were measured before and 30, 45, 60, and 75 min after oral administration of 60 mg of nateglinide. We investigated serum IRI n min after nateglinide administration (IRI_n) associatied with CPR 120 min after standard meal intake (CPR₁₂₀), and the nateglinide index n min after nateglinide administration (NGI_n) associated with the rate constant for plasma glucose disappearance after insulin injection (Kitt). We found 27 subjects with a positive relationship between CPR₁₂₀ and IRI₆₀ (r=0.56, p=0.0023) and between Kitt and NGI₆₀ (r=0.71, p<0.0001). In 50 type 2 diabetics, ROC analysis revealed that IRI₆₀ was more sensitive and specific for screening for the indication of insulin therapy for screening for glycemic control than CPR₁₂₀ when the cut-off value of IRI₆₀ was 7.8 μU/ml. ROC analysis also showed that NGI₆₀ sensitivity and specificity for screening for the insulin sensitizer were similar to those of Kitt when NGI₆₀ was 1.0 0/000 min^-1 μU^-1. We concluded that IRI₆₀ and NGI₆₀ are clinically useful parameters in deciding how to treat type 2 diabetics.