title: Method of insulin administration has no effect on insulin sensitivity estimates from the insulin-modified minimal model protocol.
abstract: The effect of the method of insulin administration on insulin sensitivity estimates from the insulin modified minimal model (MINMOD) protocol was evaluated using the tolbutamide-boosted protocol as a reference. The study included 21 nondiabetic men ages 40 +/- 2 years (mean +/- SE) with a BMI of 26.6 +/- 1.1 kg/m2. Each subject underwent four frequently sampled intravenous glucose tolerance tests (FSIGTT), one with tolbutamide and three with the same insulin dosage (0.03 U/kg) given as a bolus or infusion over 5 or 10 min. The insulin sensitivity index (SI) of each subject was calculated from each FSIGTT with MINMOD. Insulin sensitivity indexes from the four FSIGTTs were highly correlated (r > 0.85, P < 0.001). SI(insulin) from the bolus and the 5- and 10-min infusion protocols were similar, but were 21 +/- 5, 29 +/- 5, and 23 +/- 4% lower than SI(tolbutamide), respectively. SG(tolbutamide) and SG(insulin) were not different among the four protocols and were significantly correlated (r > 0.55, P < 0.01). Thus the tolbutamide and insulin protocols must not be used interchangeably in any single cross-sectional or longitudinal study. When the same insulin dosage is used, the method of its administration has no bearing on insulin sensitivity estimates from the insulin-modified FSIGTT. The same method of insulin administration should be used, however, in any single study for purpose of standardization.
authors.affiliation: Department of Medicine, University of Southern California Medical School, Los Angeles 90033, USA. saad@hsc.usc.edu
authors.forename: M F
authors.initials: MF
authors.lastname: Saad
authors.forename: G M
authors.initials: GM
authors.lastname: Steil
authors.forename: M
authors.initials: M
authors.lastname: Riad-Gabriel
authors.forename: A
authors.initials: A
authors.lastname: Khan
authors.forename: A
authors.initials: A
authors.lastname: Sharma
authors.forename: R
authors.initials: R
authors.lastname: Boyadjian
authors.forename: S D
authors.initials: SD
authors.lastname: Jinagouda
authors.forename: R N
authors.initials: RN
authors.lastname: Bergman
mesh_terms: D000328:Adult; D001786:Blood Glucose / Q000378:metabolism; D005951:Glucose Tolerance Test; D006801:Humans; D007004:Hypoglycemic Agents / Q000008:administration & dosage / Q000494:pharmacology; D007262:Infusions, Intravenous; D007275:Injections, Intravenous; D007328:Insulin / Q000008:administration & dosage* / Q000097:blood / Q000494:pharmacology; D007333:Insulin Resistance; D007700:Kinetics; D008297:Male; D008954:Models, Biological; D014044:Tolbutamide / Q000008:administration & dosage / Q000494:pharmacology
chemical_list: D001786:Blood Glucose; D007004:Hypoglycemic Agents; D007328:Insulin; D014044:Tolbutamide