Abstract
Recently, we proposed a model describing the suppression of endogenous glucose production (EGP) during a meal. It assumes that EGP suppression depends on glucose concentration and its rate of change and on delayed insulin action. Hepatic insulin sensitivity (S(I)(Lmeal)) can be derived from EGP model parameters. This model was shown to adequately describe EGP profiles measured with multiple tracer techniques; however, S(I)(Lmeal) has never been compared directly with its euglycemic hyperinsulinemic clamp counterpart (S(I)(Lclamp)). To do so, 62 subjects with different degrees of glucose tolerance underwent a triple-tracer mixed meal. Fifty-seven subjects also underwent a labeled ([3-(3)H]glucose) euglycemic hyperinsulinemic clamp. From the triple-tracer meal data, virtually model-independent estimates of EGP were obtained using the tracer-to-tracee clamp technique, and the EGP model was identified in each subject. Model fit was satisfactory, and S(I)(Lmeal) was estimated with good precision. Correlation between S(I)(Lclamp) and S(I)(Lmeal) was good (r = 0.72, P < 0.001); however, S(I)(Lmeal) was lower than S(I)(Lclamp) (4.60 ± 0.64 vs. 8.73 ± 1.07 10(-4) dl·kg(-1)·min(-1) per μU/ml, P < 0.01). This difference may be due to different ranges of insulin explored during the two tests (ΔI(clamp) = 15.60 ± 1.61 vs. ΔI(meal)= 83.37 ± 10.71 μU/ml) as well as steady- vs. non-steady-state glucose and insulin profiles. In conclusion, the new EGP model provides an estimate of hepatic insulin sensitivity during a meal that is in good agreement with that derived in the same individuals with a hyperinsulinemic clamp. When used in conjunction with the minimal model, the approach potentially enables estimation of hepatic insulin sensitivity from a single-tracer labeled meal or oral glucose tolerance test.