A Simple Method for Quantitation of Insulin Sensitivity and Insulin Release from an Intravenous Glucose Tolerance Test

Abstract

Both insulin secretion and insulin sensitivity are important in the development of diabetes but current methods used for their measurements are complex and cannot be used for epidemiological surveys. This study describes a simplified approach for the estimation of first phase insulin release and insulin sensitivity from a standard 40-min intravenous glucose tolerance test (IVGTT), and compares these parameter estimations with the sophisticated minimal model analysis of a frequently sampled 3-h IVGTT and the euglycaemic clamp technique. For the simplified IVGTT, first phase insulin release was measured as the insulin area above basal post glucose load unit-1 incremental change (i.e. peak rise) in plasma glucose over 0-10 min, and insulin sensitivity as a rate of glucose disappearance (Kg) unit-1 insulin increase above basal from 0-40 min post-glucose load in 18 subjects who were studied twice, either basally or in a perturbed pathophysiological state (i.e. pre- and post-ultramarathon race, n = 5; pre- and post-20 h pulsatile hyperinsulinaemia, n = 8; pre- and post-thyrotoxic state, n = 5). A further 12 subjects were compared by IVGTT, and glucose clamp. In addition, seven dogs were studied three times by IVGTT during normal saline infusion and after short-term (1/2 hour) or long-term (72 hour) adrenaline infusions. First phase insulin release and insulin sensitivity estimated from the simplified IVGTT as calculated by the two methods correlated closely (rs = 0.89 and rs = 0.87, respectively), although less precisely in markedly insulin-resistant subjects and the slopes and y intercepts of the linear regression lines were similar in the basal and perturbed states.(ABSTRACT TRUNCATED AT 250 WORDS)

Common polymorphisms of calpain-10 are associated with abdominal obesity in subjects at high risk of type 2 diabetes

“…First, an IVGTT was performed to determine the first-phase insulin secretion capacity [18] as previously described [16]. Immediately after an IVGTT, the degree of insulin resistance was evaluated by the euglycaemic clamp technique [19].…”

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

“…A simple method for quantification of insulin sensitivity from an IVGTT (K g /D incremental IRI 0±40 min ) has been reported [46]. This alternative analysis could be of value in conditions where traditional reference procedures (clamp or FSIVGTT-MinMod) are not feasible.…”

The effect of birthweight upon insulin resistance and associated cardiovascular risk factors in adolescence is not explained by fetal growth velocity in the third trimester as measured by repeated ultrasound fetometry

“…Basal blood samples were drawn. A simplified IVGTT [21] was performed using a glucose bolus (20%) (300 mg/kg bodyweight) infused over 1 min and subsequent blood sampling. We measured: waist and hip circumference (using soft tape at the umbilicus and at the widest part of the gluteal region, respectively), skinfold thickness (at biceps, triceps and sub-scapularis using a Harpenden skinfold calliper), height to the nearest 0.1 cm (using a calibrated wall-mounted stadiometer; Force Institute, Broendby, Denmark) and weight (kg) (using a digital weight scale with a precision of 0.01 kg; Lindeltronic 8000; Copenhagen, Denmark).…”

“…According to the methods described by Galvin et al [21] and using the trapezoidal rule we calculated: first-phase insulin response (FPIR) (Δ insulin area above basal 0−10min /Δ glucose peak above basal 0−10min ), glucose disappearance rate (K g ) (-2.303 × slope of log glucose concentration 10−40min ) and insulin sensitivity (SI) (K g /Δ insulin area above basal 0−40min ). Disposition index (DI) representing insulin secretion corrected for the ambient degree of insulin resistance was calculated (SI×Δ insulin area 0−10min ).…”