Journal of General Internal Medicine

, Volume 15, Issue 8, pp 551–555

Revisiting the oral glucose tolerance test criterion for the diagnosis of diabetes

  • Mayer B. Davidson
  • David L. Schriger
  • Anne L. Peters
  • Brett Lorber
Original Articles

DOI: 10.1046/j.1525-1497.2000.08024.x

Cite this article as:
Davidson, M.B., Schriger, D.L., Peters, A.L. et al. J GEN INTERN MED (2000) 15: 551. doi:10.1046/j.1525-1497.2000.08024.x

Abstract

OBJECTIVE: The Expert Committee on the Diagnosis and Classification of Diabetes retained the 2-hour glucose concentration on an oral glucose tolerance test of ≥11.1 mmol/L (200 mg/dL) as a criterion to diagnose diabetes. Since glycated hemoglobin levels have emerged as the best measure of long-term glycemia and an important predictor of microvascular and neuropathic complications, we evaluated the distribution of hemoglobin A1C (Hb A1C) levels in individuals who had undergone an oral glucose tolerance test to determine how well 2-hour values could identify those with normal versus increased Hb A1C levels.

DESIGN: A cross-sectional analysis of 2 large data sets was performed. We cross-tabulated 2-hour glucose concentrations on an oral glucose tolerance test separated into 4 intervals (<7.8 mmol/L [140 mg/dL], 7.8–11.0 mmol/L [140–199 mg/dL], 11.1–13.3 mmol/L [200–239 mg/dL], and ≥13.3 mmol/L [240 mg/dL]) with Hb A1C levels separated into 3 intervals (normal; <1% above the upper limit of normal; and greater than or equal to the upper limit of normal +1%).

RESULTS: Approximately two thirds of patients in both data sets with 2-hour glucose concentrations of 11.1 to 13.3 mmol/L (200–239 mg/dL) had normal Hb A1C levels. In contrast, 60% to 80% of patients in both data sets with 2-hour glucose concentrations ≥13.3 mmol/L (240 mg/dL) had elevated Hb A1C levels.

CONCLUSION: Since Hb A1C levels are the best measures presently available that reflect long-term glycemia, we conclude that the 2-hour glucose concentration criterion on an oral glucose tolerance test for the diagnosis of diabetes should be raised from ≥11.1 mmol/L (200 mg/dL) to ≥13.3 mmol/L (240 mg/dL) to remain faithful to the concept that diagnostic concentrations of glucose should predict the subsequent development of specific diabetic complications (e.g., retinopathy).

Key words

oral glucose tolerance test glycated hemoglobin Hb A1C diagnosis of diabetes 

Copyright information

© Society of General Internal Medicine 2000

Authors and Affiliations

  • Mayer B. Davidson
    • 1
    • 2
  • David L. Schriger
    • 3
  • Anne L. Peters
    • 2
  • Brett Lorber
    • 3
  1. 1.the Charles R. Drew University of Medicine and ScienceLos Angeles
  2. 2.Department of MedicineUniversity of California, Los Angeles School of MedicineLos Angeles
  3. 3.Department of Emergency MedicineUniversity of California, Los Angeles School of MedicineLos Angeles
  4. 4.Clinical Trials UnitLos Angeles