title: Repeatability of insulin sensitivity and glucose effectiveness from the minimal model. Implications for study design.
abstract: To determine the repeatability of insulin sensitivity measurements generated by the minimal model, we subjected 11 normal men to 3 frequently sampled intravenous glucose tolerance tests (FSIGTs) over the course of 12 days under conditions of fixed diet and limited physical activity. FSIGTs were analyzed by the minimal model using a full, 30-sample data set, as well as a reduced, 12-sample data set that has been proposed for population studies. Minimal model insulin sensitivity index (SI) calculated from the 30-sample data set averaged 0.8 +/- 0.083 x 10(-4) min-1.(pmol/l)-1 (range 0.10-1.64 x 10(-4) min-1.(pmol/l)-1 with an average interday coefficient of variation (CV) of 20.2 +/- 3.2% (range 6-44%). Glucose effectiveness (SG) was slightly less repeatable, with an average interday variability of 25.1 +/- 8.8%. The mean CVs for first-phase insulin secretion (20.1 +/- 3.5%) and total insulin secretion (21.4 +/- 3.2%) were similar to the CV for SI. Mean insulin sensitivity calculated from the 12-sample data set (0.82 +/- 0.08 x 10(-4) min-1.(pmol/l)-1 was not significantly different from the mean calculated from the full data set (P = 0.37, paired Student's t test). However, the mean CV of SI calculated from the reduced data set tended to be greater than that calculated from the full data set (27.7 +/- 5.4% vs. 20.2 +/- 3.2%).(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Department of Medicine, University of Southern California, School of Medicine, Los Angeles.
authors.forename: G M
authors.initials: GM
authors.lastname: Steil
authors.forename: J
authors.initials: J
authors.lastname: Murray
authors.forename: R N
authors.initials: RN
authors.lastname: Bergman
authors.forename: T A
authors.initials: TA
authors.lastname: Buchanan
mesh_terms: D000328:Adult; D001786:Blood Glucose / Q000032:analysis*; D005951:Glucose Tolerance Test; D006801:Humans; D007333:Insulin Resistance / Q000502:physiology*; D008297:Male; D008954:Models, Biological; D012016:Reference Values; D015203:Reproducibility of Results; D012107:Research Design
chemical_list: D001786:Blood Glucose