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[Insulin tolerance test. A useful test to determine insulin resistance in obese hyperandrogenic women]
1Unidad de Endocrinología, Facultad de Medicina, Universidad de Chile, Hospital San Juan de Dios.
Background:
Insulin tolerance test is a simple method to measure insulin resistance that has a good correlation with glucose clamp studies.
Aim:
To use the insulin tolerance test to detect differences in insulin sensitivity between healthy and obese hyperandrogenic women and to correlate its results with those of the minimal model intravenous glucose tolerance test.
Patients And Methods:
Five healthy women aged 27 +/- 7 years old with a body mass index of 21 +/- 2 kg/m2 and six hyperandrogenic women aged 25 +/- 4 years old with a body mass index of 40 +/- 5 kg/m2 were studied after a 10 hours fast. For the insulin tolerance test 0.1 U/kg of crystalline insulin were injected intravenously and blood samples were drawn to measure glucose at -5,0,3,5,10 and 15 min. after the injection. Insulin resistance was calculated using the slope of descending blood glucose levels (SI1). For the intravenous glucose tolerance test, 29 blood glucose samples were obtained after an intravenous injection of 0.3 g glucose/kg followed by an injection of 0.02 U/kg of crystalline insulin. Insulin sensitivity (SI2) was calculated using Bergman's minimal model.
Results:
Healthy women had a SI1 of 0.58 (range 0.53-0.63) and a SI2 of 7.9 x 10(-4) x min-1/microU/ml (range 4.15-9.11). For hyperandrogenic women were 0.18 (range 0.06-0.29) and 0.9 x 10(-4) x min-1/microU/ml (range 0.46-1.79), respectively. Both methods had a positive correlation coefficient of 0.859 (p < 0.001).
Conclusions:
Insulin tolerance test is a good method to measure insulin resistance and has a good correlation with the frequently sampled intravenous glucose tolerance test.