A simple intravenous glucose tolerance test for assessment of insulin sensitivity

Background: The aim of the study was to find a simple intravenous glucose tolerance test (IVGTT) that can be used to estimate insulin sensitivity. Methods: In 20 healthy volunteers aged between 18 and 51 years (mean, 28) comparisons were made between kinetic parameters derived from a 12-sample, 75-min IVGTT and the M-bw (glucose uptake) obtained during a hyperinsulinemic euglycemic glucose clamp. Plasma glucose was used to calculate the volume of distribution (V-d) and the clearance (CL) of the injected glucose bolus. The plasma insulin response was quantified by the area under the curve (AUC(ins)). Uptake of glucose during the clamp was corrected for body weight (M-bw). Results: There was a 7-fold variation in M-bw. Algorithms based on the slope of the glucose-elimination curve (CL/Vd) in combination with AUCins obtained during the IVGTT showed statistically significant correlations with M-bw, the linearity being r(2) = 0.63-0.83. The best algorithms were associated with a 25-75(th) prediction error ranging from -10% to +10%. Sampling could be shortened to 30-40 min without loss of linearity or precision. Conclusion: Simple measures of glucose and insulin kinetics during an IVGTT can predict between 2/3 and 4/5 of the insulin sensitivity.