STUDY OF THE RATE OF EARLY GLUCOSE DISAPPEARANCE FOLLOWING INSULIN INJECTION - INSULIN SENSITIVITY INDEX

The euglycaemic hyperinsulinaemic glucose clamp is usually considered as the reference technique to evaluate insulin sensitivity. As it is a n expensive and time-consuming tool, we therefore tried to validate a simple insulin tolerance test (ITT) (IV bolus of 0.1 IU/kg of regular insulin, with glucose sampling at -5, 0, 3, 5, 7, 10 and 15 min) and t o demonstrate its usefulness. Insulin sensitivity was measured by DG/G 0 ratio (G0 = initial glycaemia, DG is the variation between G0 and th e glycaemia obtained at 15 min by the calculation of the regression pl ot). We confirmed the existence of a correlation between the glucose u ptake (mg/kg per min) evaluated by glucose clamp and the DG/G0 index ( r = 0.9, P < 0.01). There was no stimulation of hormonal counter regul ation during the test. The ITT was significantly correlated both with fasting insulin (r = -0.43, P < 0.01), and post-glucose load insulin c oncentration (r = -0.67, P < 0.01); each measurement expressing insuli n sensitivity. Four groups of patients with different insulin sensitiv ity: controls, NIDDM, gynoid and android obese subjects, were clearly separated by ITT. We showed that fasting glycaemia and DG/G0 were corr elated (y = 2.63/x - 0.093; r = 0.82, P < 0.01). These results suggest that ITT could be an easy, quick and low cost method to evaluate insu lin resistance in clinical practice and epidemiological studies.