TY - JOUR
T1 - Use of labeled oral minimal model to measure hepatic insulin sensitivity
AU - Man, Chiara Dalla
AU - Toffolo, Gianna
AU - Basu, Rita
AU - Rizza, Robert A.
AU - Cobelli, Claudio
PY - 2008/11
Y1 - 2008/11
N2 - The ability to accurately quantify indexes of the individual role of glucose (GEL) and insulin (SIL) in the suppression of endogenous glucose production (EGP) would improve the understanding of liver metabolism. Measuring these indexes during an IVGTT by minimal modeling of tracer labeled and unlabeled glucose data is often unreliable, possibly due to an inadequate description of EGP included in the Minimal Model. Moreover, a validation of the assumptions of the Minimal Model on EGP data has never been done. Recently, Krudys et al. (Krudys KM, Dodds MG, Nissen SM, Vicini P. Am J Physiol Endocrinol Metab 288: E1038-E1046, 2005) have proposed a PK/PD (pharmacokinetic/pharmacodynamic) model of the EGP profile that occurs during an intravenous glucose tolerance test (IVGTT); however, this model has also not been validated. The aim of this study was thus to test the Minimal Model, the PK/PD model, and six alternative EGP descriptions on recent model-independent EGP data of 20 subjects obtained with a triple-tracer meal protocol. Model performance was compared in terms of data fit, precision of the estimated parameters, and physiological plausibility. Neither the PK/PD nor the traditional Minimal Model were able to accurately describe EGP data or provide reliable estimates of the indexes. In contrast, one of the new models performed best by showing a good fit and providing accurate and precise estimates of hepatic sensitivity indexes: GEL = 0.013 ± 0.001 dl·kg-1·min-1; SI L = 5.34 ± 0.47 10-4 dl·kg-1·min -1 per μU/ml (42 and 34%, respectively, of total sensitivity indexes GETOT and SI TOT). Although this model requires further validation, it has the potential to improve our understanding of the role of the liver in pathophysiological states.
AB - The ability to accurately quantify indexes of the individual role of glucose (GEL) and insulin (SIL) in the suppression of endogenous glucose production (EGP) would improve the understanding of liver metabolism. Measuring these indexes during an IVGTT by minimal modeling of tracer labeled and unlabeled glucose data is often unreliable, possibly due to an inadequate description of EGP included in the Minimal Model. Moreover, a validation of the assumptions of the Minimal Model on EGP data has never been done. Recently, Krudys et al. (Krudys KM, Dodds MG, Nissen SM, Vicini P. Am J Physiol Endocrinol Metab 288: E1038-E1046, 2005) have proposed a PK/PD (pharmacokinetic/pharmacodynamic) model of the EGP profile that occurs during an intravenous glucose tolerance test (IVGTT); however, this model has also not been validated. The aim of this study was thus to test the Minimal Model, the PK/PD model, and six alternative EGP descriptions on recent model-independent EGP data of 20 subjects obtained with a triple-tracer meal protocol. Model performance was compared in terms of data fit, precision of the estimated parameters, and physiological plausibility. Neither the PK/PD nor the traditional Minimal Model were able to accurately describe EGP data or provide reliable estimates of the indexes. In contrast, one of the new models performed best by showing a good fit and providing accurate and precise estimates of hepatic sensitivity indexes: GEL = 0.013 ± 0.001 dl·kg-1·min-1; SI L = 5.34 ± 0.47 10-4 dl·kg-1·min -1 per μU/ml (42 and 34%, respectively, of total sensitivity indexes GETOT and SI TOT). Although this model requires further validation, it has the potential to improve our understanding of the role of the liver in pathophysiological states.
KW - Glucose kinetics
KW - Insulin resistance
KW - Meal
KW - Tracer
UR - http://www.scopus.com/inward/record.url?scp=57049181334&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=57049181334&partnerID=8YFLogxK
U2 - 10.1152/ajpendo.00486.2007
DO - 10.1152/ajpendo.00486.2007
M3 - Article
C2 - 18765681
AN - SCOPUS:57049181334
SN - 0193-1849
VL - 295
SP - E1152-E1159
JO - American Journal of Physiology - Endocrinology and Metabolism
JF - American Journal of Physiology - Endocrinology and Metabolism
IS - 5
ER -