Publication:

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

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.