Estimation of insulin sensitivity and glucose clearance from minimal model: new insights from labeled IVGTT
The ''minimal model'' of glucose disappearance provides noninvasive estimates of insulin sensitivity and glucose effectiveness from an intravenous glucose tolerance test (IVGTT). However, this model does not allow the separation of glucose production from utilization. To overcome this limitation, labeled glucose was injected along with cold glucose in six normal dogs, and both cold and labeled glucose time courses were monitored along with insulin concentration. A revised minimal model was fitted to tracer data to obtain new measures of insulin sensitivity (SI* = 6.41 +/- 0.91 10(-4) min-1 X microU-1 X ml-1) and fractional glucose clearance (SG* = 0.0092 +/- 0.0009 min-1). SG* was compared with a direct measure obtained by a hepatic arterial-venous difference technique, which yielded a value of 0.0097 +/- 0.0002, virtually identical to SG*, thereby validating the model estimate. When the original minimal model was identified from cold data, we obtained S1 = 4.52 +/- 1.39 and SG = 0.042 +/- 0.009. SI* and SG* were different from SI and SG, respectively. In particular SG overestimates fractional glucose clearance by approximately five times. The revised minimal model yields glucose disposal parameters SI* and SG* that are not affected by the confounding effect of insulin and glucose inhibition of glucose production. Limitations inherent in cold IVGTT and original minimal model are overcome by labeled IVGTT and the revised minimal model, while test simplicity remains.
- Research Organization:
- Univ. of Padua, Italy
- OSTI ID:
- 5578624
- Journal Information:
- Am. J. Physiol.; (United States), Journal Name: Am. J. Physiol.; (United States)
- Country of Publication:
- United States
- Language:
- English
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GLUCOSE
CLEARANCE
METABOLISM
BIOCHEMICAL REACTION KINETICS
BIOLOGICAL MODELS
DOGS
INSULIN
LABELLED COMPOUNDS
LIVER
RADIOISOTOPES
TRACER TECHNIQUES
ALDEHYDES
ANIMALS
BODY
CARBOHYDRATES
DIGESTIVE SYSTEM
GLANDS
HEXOSES
HORMONES
ISOTOPE APPLICATIONS
ISOTOPES
KINETICS
MAMMALS
MONOSACCHARIDES
ORGANIC COMPOUNDS
ORGANS
PEPTIDE HORMONES
REACTION KINETICS
SACCHARIDES
VERTEBRATES
550501* - Metabolism- Tracer Techniques