Published: 2018-06-27

Glycated haemoglobin versus oral glucose tolerance test in screening for gestational diabetes mellitus

S. Arthy, I. Arun


Background: Glycated haemoglobin (HbA1c) has been documented as an easier, useful tool in diagnosis of diabetes and can be considered as a screening tool in GDM as compared to oral glucose tolerance test (OGTT) which has practical constraints like long waiting period in fasting, too many pricks and non-compliance to glucose load solution. The objective of the study was to find out the utility of HbA1c as a diagnostic tool when compared with OGTT in screening of GDM.

Methods: A retrospective study was conducted at Sri Venketeswaraa Medical College, Hospital and Research Center, Puducherry including 500 antenatal women attending to the Department of Obstetrics and Gynaecology for their ante-natal checkup during the period from August 2016 to April 2018. HbA1c levels were estimated and ROC curve analysis was done to estimate sensitivity and specificity against gold standard OGTT.

Results: The HbA1c levels among the study subjects varied from 4.3% to 8.2%. The mean HbA1c levels among those diagnosed as GDM by gold standard OGTT was 5.82±1.1% and among those without GDM was 5.13±0.7%. The area under the ROC curve was 0.773 (95% CI 0.732–0.814). An HbA1c cut-off value of ≥5.91% had sensitivity of 34.6% and Specificity of 98.2% in diagnosing GDM. An HbA1c cut-off value of ≥5.32% had sensitivity of 84.8% and specificity of 60.1% in diagnosing GDM.

Conclusions: HbA1c levels cannot substitute OGTT in diagnosis of GDM. A higher specific cut-off HbA1c value of ≥5.95% is diagnostic of GDM.


HbA1c, OGTT, Gestational diabetes mellitus, Sensitivity and specificity

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World Health Organization. Diagnostic Criteria and Classification of Hyperglycaemia First Detected in Pregnancy. Geneva: World Health Organization; 2013.

Casey BM, Lucas MJ, McIntire DD, Leveno KJ. Pregnancy outcomes in women with gestational diabetes compared with the general obstetric population. Obstet Gynecol. 1997;90:869-73.

World Health Organisation. Use of glycated haemoglobin (HbA1c) in diagnosis of diabetes mellitus, WHO/NMH/CHP/ CPM/11.1 ed., Geneva: World Health Organisation; 2011.

American Diabetes Association. Diagnosis and classification of diabetes mellitus. Diabetes Care 2010;33(1):62-9.

Balaji V, Madhuri BS, Ashalatha S, Sheela S, Suresh S, Seshiah V. A1c in gestational diabetes mellitus in Asian Indian women. Diabetes Care. 2007;30:1865-7.

Lind T, Cheyne GA. Effect of normal pregnancy upon the glycosylated haemoglobins. Br J Obstet Gynaecol. 1979;86:210-3.

Nielsen LR, Ekbom P, Damm P, Glu¨ mer C, Frandsen M, Jensen DM, et al. HbA1c levels are significantly lower in early and late pregnancy. Diabetes Care. 2004;27:1200-1.

Mosca A, Paleari R, Dalfra MG, Di Cianni G, Cuccuru I, Pellegrini G, et al. Reference intervals for hemoglobin A1c in pregnant women: data from an Italian multicenter study. Clin Chem. 2006;52:1138-43.

International Association of Diabetes Pregnancy Study Groups. International Association of Diabetes and Pregnancy Study Groups recommendations on the diagnosis and classification of hyperglycemia in pregnancy. Diabetes Care. 2010;33:676-82.

Seshiah V, Balaji V, Balaji MS, Sanjeevi CB, Green A. Gestational diabetes mellitus in India. J Assoc Physicians India. 2004;52:707-11.

Balaji V, Madhuri BS, Ashalatha S, Sheela S, Suresh S, Seshiah V. A1c in gestational diabetes mellitus in Asian Indian women. Diabetes Care. 2007;30:1865-7.

Barr RG, Nathan DM, Meigs JB, Singer DE. Tests of glycemia for the diagnosis of type II diabetes mellitus. Ann Intern Med. 2002;137:263-72.

Rajput R, Yadav Y, Rajput M, Nanda S. Utility of HbA1c for diagnosis of gestational diabetes mellitus. Diabetes Res Clin Pract. 2012;98(1):104-7.