Reproducibility of the Short Insulin Tolerance Test

Abstract

The short insulin tolerance test is a simple method of estimating insulin resistance by measuring the rate of fall of blood glucose following the intravenous administration of insulin. To determine its reproducibility, 18 healthy subjects underwent duplicate insulin tolerance tests separated by at least 1 week. Intravenous insulin (0.05 units kg-1) was administered into an antecubital vein and arterialized venous samples were obtained from a retrogradely cannulated vein on the dorsum of the hand on the same side. The test was terminated with an intravenous glucose injection 15 min after the administration of insulin. The mean whole blood glucose concentration fell from 4.6 mmol l-1 to 2.8 mmol l-1 while plasma insulin concentrations rose to supraphysiological levels and declined exponentially. The glucose disappearance rate (Kitt) calculated from the slope of the fall in log transformed blood glucose between 3 and 15 min after insulin injection ranged from 2.1 to 6.5 (mean 4.4) % min-1 during the first visit and 1.7 to 7.4 (mean 4.4) % min-1 during the second. The ratio of the within-subject to between-subject variance of the test was 0.24, the within-subject coefficient of variation was 13% and the between-subject coefficient of variation 26%. The short insulin tolerance test is reproducible and could be used to measure insulin resistance in large-scale epidemiological studies.

Comparison of insulin sensitivity tests across a range of glucose tolerance from normal to diabetes

“…The short ITT is reported to have good precision (at an insulin dose of 0.1 UI/kg), with a CV of 6 % in obese NGT subjects [47] and 9 % in normal subjects [28], whereas in non-obese NGT subjects and using a 0.05 UI/kg insulin bolus within-subject CVs of 13 % has been reported [48]. With this dose we found CVs of about 30 % in our group spanning the range of glucose tolerance.…”

Relation of triglyceride stores in skeletal muscle cells to central obesity and insulin sensitivity in European and South Asian men

“…A standard 75-g oral glucose tolerance test was done to measure fasting and 2-h glucose, insulin and NEFA. Insulin sensitivity was measured by the short insulin tolerance test [8], during which the insulin sensitivity index (ISI, %/min) is derived from linear regression of the rate of fall of log glucose from 3 to 15 min after a bolus of intravenous insulin (0.05 units/kg). Physical activity was assessed by three methods: (1) subjects rated themselves as much less active (i), somewhat less active (ii), about as active (iii), somewhat more active (iv), or much more active (v) compared with others their age; (ii) subjects stated if they participated in any regular sport (% active), and (iii) how far they walked daily [ < 1/4 mile (1), 1/4 to 1 mile (2), 1±3 miles (3), or > 3 miles (4)].…”

Determining the relationship between dietary carbohydrate intake and insulin resistance

“…The 'frequently sampled intravenous glucose tolerance test' (Bergman et al 1979) can be modified with a bolus injection of intravenous insulin (Beard et al 1986;Yang et al 1987) or the insulinotropic hypoglycaemic sulfonylurea, tolbutamide (Finegood et al 1990), and so be improved in its sensitivity and reproducibility (Beard et al 1986;Bergman et al 1989;Saad et al 1994). An alternative approach is the 'insulin tolerance test' that determines insulin sensitivity from the glucose-lowering rate of intravenous insulin administration (Bonora et al 1989;Hirst et al 1993).…”