Insulin sensitivity from meal tolerance tests: a computer program

Recently, a new approach was introduced that allows estimation of insulin sensitivity [S[l]] from orally ingested glucose during an OGTT, or a meal glucose tolerance test [MGTT]. S1 from the MGTT was strongly correlated to the S[l] values obtained from an insulin-modified, frequently sampled intravenous glucose test [FSIGT], which is considered as one of the gold standards. This new method makes use of MGTT/OGTT data, which are relatively much easier to obtain. This makes this method of value in the assessment of insulin sensitivity in various circumstances in which the use of clamps or the minimal model is impractical. For epidemiological studies, screening of high-risk populations, and large-scale intervention trials, S[l] calculations would be rather tedious and time-consuming. Therefore, it was thought to develop a computer program to carry out the calculations quickly and accurately. Ten healthy subjects [4 men and 6 women; age 47 +/- 2.6 years; body mass index 25.9 +/- 1.2 kg/m[2]], with normal glucose tolerance. The studied subjects received, on different occasions, a meal tolerance test [MGTT]. The meal was eaten within 10 mm. Blood samples were collected at - 30, - 1, 10, 20, 30, 40, 50, 60, 75, 90, 120, 150, 180, 210, and 240 mm. Plasma glucose and serum insulin were determined in the blood samples. A computer program, COBELLBAS, was developed. It computes the insulin sensitivity SI[oral] from MGTT/OGTT data. Use is made of function AREA to calculate the areas under the curves, and function FUN1 for interpolation. The computer program was tested, and results comparable with the published ones were obtained. The computer program was tested, and satisfactory results were obtained

Evaluation of simpler methods for the assessment of insulin sensitivity in Egyptians

Aim: A number of insulin sensitivity indices are frequently used. These are fasting insulin [I], 40/1, HOMA-IR, n[HOMA], 1/HOMA, I/G, and G/l, where G and I are the fasting glucose, and insulin concentrations, respectively. To test the validity of these simple indices in Egyptians, their values were computed and correlated with the MINMOD-derived S1 value. Subjects and The present study was carried out on 40 Egyptian subjects [15 obese and 25 nonobese]. The weight and height were measured from which the BMI was calculated. Skinfold thickness was measured from the biceps, triceps, subscapular and supra-iliac region. The body fat content was calculated. Waist and hip circumference were measured from which waist/hip ratio was calculated. All subjects underwent a 75 g OGTT followed, at least 7 days later, by an FSIVGTT. Plasma glucose was determined and serum insulin was measured by EASIA. Insulin sensitivity, S1, and glucose effectiveness, SG, were calculated with the MINMOD program. The insulin sensitivity indices were also calculated from the fasting insulin [I], fasting glucose [G], 40/I, HOMA-IR, In [HOMA], 1/HOMA and G/l. A significant correlation was found between S1, and I, 40/I, HOMA-IR, in [HOMA], 1/HOMA, I/G and G/l. Ln [HOMA], G/l, 40/I and HOMA-IR correlated better with MINMOD S1, than I, 1/HOMA, I/G and G. Conclusions: These simple S1 indices give only approximate values which cannot be counted upon in all cases. Further studies are needed to characterize the validity of these simple indices in terms of the factors responsible for insulin sensitivity, to validate these measures in different populations and to clarify the differences between different studies