title: Reproducibility and comparability of insulin sensitivity indices measured by stable-label intravenous glucose tolerance test.
abstract: We have investigated the reproducibility of (1) insulin sensitivity (S*I) and glucose effectiveness (S*G) as measured by the stable-label (one compartment) minimal model, and (2) insulin sensitivity (S*Ib), plasma clearance rate (PCR), basal hepatic output (HGOb), and total hepatic glucose output (HGO0-240) as measured by the novel stable-label two compartment model of glucose disappearance during labelled intravenous glucose tolerance test (IVGTT) using 6,6-(2)H-glucose. Ten normal male subjects were studied on two occasions one week apart. Both models provided estimates of all indices with acceptable precision (CV of parameter estimates < or =50%). The within subject CVs of S*I and S*Ib were comparable (17% vs 19%) as were the within subject CVs of S*G and PCR (13% vs 16%). A highly significant linear relationship was observed between S*Ib and S*I (0.303 +/- 0.046 ml kg(-1) min(-1) per mU l(-1) vs 13.04 +/- 1.89 10(-4) min(-1) per mU l(-1), y = 0.0037 x + 0.0002, r = 0.90, p < 0.001; mean +/- SE), but not between PCR and S*G (1.98 +/- 0.15 ml kg(-1) min(-1) vs 0.0089 +/- 0.0005 min(-1), rs = 0.34, NS). The two compartment model provided a plausible time-profile of hepatic glucose output during IVGTT, reproducible estimates of HGOb (1.96 +/- 0.18 mg kg(-1) min(-1), 15%; mean +/- SE, within subject CV), and a highly reproducible HGO0-240 (7%; within subject CV). We conclude that the stable-label (one compartment) minimal model and the stable-label two compartment model provide reproducible estimates of parameters of glucose kinetics in normal subjects. Insulin sensitivity indices estimated by the two models are strongly linearly related.
authors.affiliation: Metabolic Modeling Group, Centre for Measurement and Information in Medicine, City University, London, UK.
authors.forename: R
authors.initials: R
authors.lastname: Hovorka
authors.forename: P
authors.initials: P
authors.lastname: Bannister
authors.forename: D J
authors.initials: DJ
authors.lastname: Eckland
authors.forename: D
authors.initials: D
authors.lastname: Halliday
authors.forename: D N
authors.initials: DN
authors.lastname: Murley
authors.forename: S E
authors.initials: SE
authors.lastname: Rees
authors.forename: M A
authors.initials: MA
authors.lastname: Young
mesh_terms: D000328:Adult; D001786:Blood Glucose / Q000378:metabolism; D003903:Deuterium; D005947:Glucose / Q000008:administration & dosage / Q000378:metabolism; D005951:Glucose Tolerance Test / Q000379:methods*; D006801:Humans; D007275:Injections, Intravenous; D007328:Insulin / Q000494:pharmacology*; D007700:Kinetics; D008099:Liver / Q000378:metabolism; D008297:Male; D008657:Metabolic Clearance Rate; D015203:Reproducibility of Results
chemical_list: D001786:Blood Glucose; D007328:Insulin; D003903:Deuterium; D005947:Glucose