Presentation of a new method for specific measurement of in vivo insulin-stimulated glucose disposal in humans: comparison of this approach with the insulin clamp and minimal model techniques.

This study was initiated to compare the abilities of two alternative approaches to the measurement of insulin-dependent glucose disposal in normal humans. The ability of insulin to stimulate glucose disposal was measured in 12 normal subjects by determining glucose disposal rates during insulin clamp studies carried out at both basal insulin concentrations (approximately 6 microU/ml) and during a period of sustained hyperinsulinemia (approximately 60 microU/ml). The increment in glucose disposal was defined as insulin-dependent disposal and compared to estimates of insulin action generated by both the conventional insulin clamp approach and the minimal model technique. The results documented an extremely close correlation (r = 0.99; P less than 0.001) between the direct determination of insulin-dependent glucose disposal and insulin-stimulated glucose disposal as estimated by the insulin clamp technique. In contrast, there was a poor correlation (r = 0.44; P = NS) between insulin sensitivity as estimated by the minimal model technique and insulin-dependent glucose disposal. These results indicate that the value of glucose disposal determined by the insulin clamp approach, which includes both insulin-independent and insulin-dependent glucose disposal, provides an excellent estimate of insulin-dependent glucose disposal in subjects with normal glucose tolerance. Unfortunately, this does not appear to be true of the minimal model technique. However, it must be emphasized that these conclusions are only applicable to normal humans, and may not apply to normal subjects of other species or to humans under different physiological or pathological situations.