Relationship Between Insulin Response During the Intravenous Glucose Tolerance Test, Rate of Fractional Glucose Removal and the Degree of Insulin Resistance in Normal Adults

We studied the relationship between the absolute insulin response during the intravenous glucose tolerance test (IVGTT) and both the fractional glucose disposal rate (KG) during the IVGTT and the degree of insulin resistance as measured by a separate infusion study, the pancreatic suppression test (PST), in normal adults. Insulin response during the IVGTT was analyzed in four ways: (1) early (area under the one, three and five minute response curve); (2) middle (ten minute insulin value); (3) late (area under the twenty to sixty minute response curve); and (4) total (area under the entire response curve). Only weak to modest correlations existed between the four measures of insulin response and KG, and the only statistically significant correlation (r = .39, p < .05) existed between the middle insulin response and KG. However, significant correlations were found between the degree of insulin resistance measured during the PST and the early (r = .40, p < .05), middle (r = .59, p < .005), late (r = .71, p < .001) and total (r = .66, p < .001) insulin responses. Whereas the height of the insulin response during an IVGTT has only a modest correlation with the KG, it correlates quite well with the degree of insulin resistance.