The intravenous insulin tolerance test is an accurate method for screening a general population for insulin resistance and related abnormalities

To verify whether the short intravenous insulin tolerance test (ITT) (a safe, reproducible, inexpensive, rapid and easy to perform measurement of insulin sensitivity) is a suitable test for insulin resistance screening in a general population, we measured in 60 non diabetic subjects, either non-obese (no.=40) or obese (BMI>28, no.=20) the K of glucose disappearance from plasma after ITT (K-ITT), plasma glucose (PG) and insulin (IRI) both fasting (FPG, FIRI) and at 120 min of OGTT (PG- 120, IRI- 120), and also triglycerides (Tg), cholesterol (Chol) and blood pressure (BP). Subjects were subdivided into quartiles according to K-ITT values. Average FPG, PG-120, FIRI, IRI-120, Tg and Chol values were progressively increased, and average HDL/Chol was progressively decreased from quartile 1 (the most insulin sensitive) to 4 (the most insulin resistant) (p<0.05, by 1-way ANOVA test). Also BP was increased in the insulin resistant patients, but statistical significance was not reached. Three or more of the studied parameters (FPG and/or PG-120, FIRI and/or IRI-120, Tg, HDL/Chol, mean BP) were altered (below the worst 25 degrees percentile) in 64% of subjects from quartile 4; none of the subjects in quartile 1 was affected by such a cluster of alterations. K-ITT values less than or equal to 4.8 identified the cluster of insulin resistance related alterations with an accuracy of 82% (sensitivity=83.3%, specificity=80.5%). In healthy subjects with a wide range of BMI the ITT is a reliable procedure for screening for the cluster of metabolic alterations related to insulin resistance. (C) 1999, Editrice Kurtis.