Beta-cell function during insulin-modified intravenous glucose tolerance test successfully assessed by the C-peptide minimal model

Metabolism. 1999 Sep;48(9):1162-6. doi: 10.1016/s0026-0495(99)90132-4.


The insulin-modified intravenous glucose tolerance test (IM-IVGTT) is increasingly used to measure insulin sensitivity. However, the assessment of beta-cell secretion is usually made using rough indices. The aim here is to evaluate the ability of the minimal model of C-peptide secretion and kinetics recently proposed for the standard IVGTT (S-IVGTT) to also assess beta-cell function during the IM-IVGTT. C-peptide and glucose data from the IM-IVGTT in 15 normal humans were analyzed. The results show that the same rich beta-cell picture from the S-IVGTT can be obtained during an IM-IVGTT. In particular, in each individual, the time course of beta-cell secretion can be reconstructed and the functional indices of glucose control on first-phase (phi1), second-phase (phi2), and basal (phi(b)) insulin secretion can be estimated (phi1 = 191 +/- 29, phi2 = 10.9 +/- 1.4 x 10(-9) x min(-1), and phi(b) = 5.7 +/- 1.0 x 10(-9) x min(-1), mean +/- SE). Finally, the comparison between IM-IVGTT and S-IVGTT phi1, phi2, and phi(b) values suggest they are not affected by insulin administration.

Publication types

  • Clinical Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • C-Peptide / blood*
  • C-Peptide / pharmacokinetics
  • Glucose Tolerance Test / methods*
  • Humans
  • Insulin / blood
  • Insulin / pharmacology*
  • Islets of Langerhans / metabolism*
  • Kinetics
  • Middle Aged
  • Sensitivity and Specificity


  • C-Peptide
  • Insulin