Measures of Beta-Cell Function During the Oral Glucose Tolerance Test, Liquid Mixed-Meal Test, and Hyperglycemic Clamp Test

J Pediatr. 2008 May;152(5):618-21. doi: 10.1016/j.jpeds.2007.11.044. Epub 2008 Feb 4.

Abstract

Objective: To evaluate clinically useful measures of beta-cell function derived from the oral glucose tolerance test (OGTT) or mixed-meal (ie, Boost) tolerance test to assess insulin secretion in comparison with the gold standard, the hyperglycemic clamp (Hyper-C) test.

Study design: We hypothesized that OGTT/Boost-derived measures are useful estimates of beta-cell function and correlate well with insulin secretion measured by the Hyper-C test. This study was designed to assess the correlation between the ratio of the early incremental insulin/glucose responses at 15 and 30 minutes (DeltaI(15)/DeltaG(15) and DeltaI(30)/DeltaG(30)) of the OGTT and the Boost test with insulin secretion measured during the Hyper-C test (225 mg/dL). The same indices were evaluated using C-peptide. A total of 26 children (14 males, 12 females; mean age, 9.9 +/- 0.2 years; mean body mass index = 22.1 +/- 1.2 kg/m(2)) underwent a 2-hour Hyper-C test (225 mg/dL) and 3-hour OGTT and Boost tests with measurements of glucose, insulin, and C-peptide.

Results: Correlations between Hyper-C- and OGTT-derived measures of insulin secretion were stronger for the 15-minute index than for the 30-minute index of insulin secretion and stronger for C-peptide levels than for insulin levels (r = .7, P < .001 for first-phase C-peptide vs both OGTT and Boost, DeltaC(15)/DeltaG(15)).

Conclusions: In children with normal glucose tolerance, C-peptide rather than insulin level measured after 15 minutes of the OGTT or Boost test provides a reliable estimate of beta-cell function that correlates well with Hyper-C-derived insulin secretion.

Publication types

  • Randomized Controlled Trial
  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • C-Peptide / blood
  • Child
  • Female
  • Glucose Clamp Technique
  • Glucose Tolerance Test / methods*
  • Humans
  • Insulin / blood*
  • Insulin / metabolism*
  • Insulin Resistance / physiology*
  • Insulin Secretion
  • Insulin-Secreting Cells / metabolism*
  • Male
  • Overweight / metabolism*
  • Reproducibility of Results

Substances

  • C-Peptide
  • Insulin