REPEATABILITY OF INSULIN SENSITIVITY ESTI MATION USING THE MINIMAL MODEL AND COMPARISON WITH A MODIFIED SHORT LOW-DOSE INSULIN TOLERANCE-TEST

Hyperinsutinemia and insulin-resistance are metabolic disturbances ass ociated with obesity, essential hypertension, hypertriglyceridemia, gl ucose intolerance, overt non-insulin dependent diabetes mellitus, poly metabolic syndrome and atherosclerotic disease. The assessment of in v ivo insulin sensitivity (SAI in vivo) changes achieved by life style m odifications or drug interventions require a reproducible technique. T o evaluate the day-to-day intra-individual repeatability of SAI in viv o, we determined the variation in the SI index (calculated from the Mi nimal Model of Bergman modified by insulin or MMins) in II subjects wi th a wide range of insulin-resistance. SI (first study) varied from 0. 82 to 8.48 x 10(-4) min(-1)/mu U.mL (4.43 +/- 2.85 x 10(-4) min(-1)/mu U.mLmean +/- SD) and highly correlated with SI (second study) (r = 0. 89; p = 0.0002). The average interday coefficient of variation was 20. 9 +/- 13.9% and was similar in subjects with low or high SI values. We also measured SAI in vivo by assessing the rate of serum glucose decl ine induced by human cristalline insulin 0.025 U/kg IV dose after a 12 -14 hours fasting period (a modified Bonora's method or BBD) in 11 sub jects. No subject presented biochemical or symptomatic hypoglycemia. S AI in vivo values determined by BBD varied from 21 a 234 mu mol/ml/ mi n (134 +/- 64.8 mu mol/ml/min, mean +/- SD). We found a highly signifi cant correlation between SI values obtained from MMins and SAI in vivo assesed by the BBD (r = 0.89, p = 0.0002). Our results suggest that t he Mmins is a fairly reproducible procedure and that a BBD is an accep table option to quantify SAI in vivo, mainly when a fast-execution pra ctice is necessary or cost restrictions are required.