Gestational diabetes: a reappraisal of HBA1c as a screening test

Acta Obstet Gynecol Scand. 2005 Dec;84(12):1159-63. doi: 10.1111/j.0001-6349.2005.00650.x.

Abstract

Background: Recent technological advances have made HBA1c a more standardized and user-friendly test with wide availability. This study evaluated HBA1c as a screening test for gestational diabetes mellitus (GDM) in a high-risk population.

Methods: A total of 442 pregnant women were assessed by HBA1c. Two thresholds were used to "rule in or rule out" GDM, which was confirmed by the "gold-standard" 75-g OGTT (World Health Organization criteria).

Results: Eighty-four (19%) women had GDM while 358 (81%) women were normal; there was a complete overlap of the HBA1c histograms of the two populations. The area under receiver operating characteristic curve of HBA1c to detect GDM was 0.54 (95% CI 0.48-0.61). Using a value of <5.5% to rule out GDM; a sensitivity of 82.1% was achieved, with 15 (16.7%) of 90 women below the threshold being false-negatives (NPV = 83.3%). Using a threshold of HBA1c > or = 7.5% to rule-in GDM; the specificity was 95.8% with 15 (71.4%) of 21 patients over the threshold being false-positives (PPV = 28.6%). HBA1c would eliminate the need for an OGTT in 25.1% (111/442) of whom 27% (30/111) women would be misclassified. At any HBA1c threshold with an acceptable sensitivity, the false-positive rate remained high making it necessary for too many healthy women to undergo the confirmatory OGTT.

Conclusion: Despite all the progress in methodology, HBA1c remains a poor test to screen for GDM.

Publication types

  • Evaluation Study

MeSH terms

  • Adolescent
  • Adult
  • Diabetes, Gestational / blood
  • Diabetes, Gestational / diagnosis*
  • Diabetes, Gestational / epidemiology
  • Diabetes, Gestational / prevention & control
  • Female
  • Glycated Hemoglobin A / analysis*
  • Humans
  • Mass Screening / methods
  • Middle Aged
  • Predictive Value of Tests
  • Pregnancy
  • Prevalence
  • Prospective Studies
  • ROC Curve
  • Sensitivity and Specificity
  • United Arab Emirates / epidemiology

Substances

  • Glycated Hemoglobin A