MEASUREMENT OF INSULIN SENSITIVITY BY THE MINIMAL MODEL METHOD USING A SIMPLIFIED INTRAVENOUS GLUCOSE-TOLERANCE TEST - VALIDITY AND REPRODUCIBILITY

This study aimed at testing whether 12 rather than 26 plasma glucose a nd insulin determinations can be used to calculate the indices of insu lin sensitivity and of glucose effectiveness using Bergman's minimal m odel during a simple intravenous glucose tolerance test performed with out tolbutamide injection. Two intravenous glucose tolerance tests (se parated by 1 week) were performed in 7 lean normal subjects and a sing le test was performed in 9 severely obese nondiabetic subjects. Intra- subject reproducibility of insulin sensitivity was not significantly d ifferent when 26 or 12 time-points were analyzed (CV = 16.8 +/- 3.4 ve rsus 18.9 +/- 3.8 % respectively). Compared with the insulin sensitivi ty of the lean subjects, that of obese subjects was significantly (P < 0.001) and similarly reduced when using 12 (2.14 +/- 0.34 versus 7.97 +/- 1.29 10(-4) min(-1)/mU.1(-)1) rather than 26 determinations (2.13 +/- 0.42 versus 6.95 +/- 1.12 10(4) min(-1)/mU.1(-1)) respectively. G lucose effectiveness was less reproducible than insulin sensitivity an d was slightly diminished by the reduction of blood samples (relative error : -9.7 +/- 4.4 %; P < 0.05). Finally, glucose effectiveness tend ed to be slightly lower in the morbidly obese subjects than in the lea n controls with both modes of calculation. In conclusion, in non-diabe tic subjects, the insulin sensitivity index can be accurately measured during a simple intravenous glucose tolerance test, without tolbutami de injection and with only 12 blood samples. The possibility of perfor ming a simplified test should contribute to increase the use of the mi nimal model method for estimating insulin sensitivity in clinical prac tice.