Gestational diabetes: a reappraisal of HBA1c as a screening test
Article first published online: 16 NOV 2005
Acta Obstetricia et Gynecologica Scandinavica
Volume 84, Issue 12, pages 1159–1163, December 2005
How to Cite
Agarwal, M. M., Dhatt, G. S., Punnose, J. and Koster, G. (2005), Gestational diabetes: a reappraisal of HBA1c as a screening test. Acta Obstetricia et Gynecologica Scandinavica, 84: 1159–1163. doi: 10.1111/j.0001-6349.2005.00650.x
- Issue published online: 16 NOV 2005
- Article first published online: 16 NOV 2005
- Submitted 27 February, 2004Accepted 7 June, 2004
- gestational diabetes;
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 ≥ 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.