Glycohemoglobin A1c: A promising screening tool in gestational diabetes mellitus

Abstract

CONTEXT:Current screening tests for gestational diabetes mellitus (GDM) are inconvenient. Therefore, alternative screening tests for GDM are desirable. The use of glycohemoglobin A1c (HbA1c) in screening for GDM remains controversial.AIM:We undertook this study to evaluate the utility of HbA1c in screening for GDM.SETTINGS AND DESIGN:Retrospective study in a tertiary teaching hospital.MATERIALS AND METHODS:Laboratory records were reviewed to identify pregnant women who underwent both oral glucose tolerance test (OGTT) and HbA1c measurements over a 16-months period. The association of OGTT with HbA1c was evaluated.STATISTICAL ANALYSIS USED:Data were collected using SPSS software. Comparisons of the means and calculations of sensitivities were performed.RESULTS:Of 145 eligible patients, 124 had GDM and 21 patients did not, per OGTT. The percentages of patients with HbA1c values (reference range of 4.8%–6.0%) equal to or above sequential cut-point values of 5.0%, 5.5%, 6.0%, 6.5% and 7.0% (i.e., sensitivity values) were 100%, 98.4%, 87.1%, 62.9% and 39.5%, respectively. The mean HbA1c of the patients with GDM was 6.9 + 0.8% compared to 6.4 + 0.6% for those without GDM (P< 0.006). At an arbitrary cut-off value of 6.0% (the upper limit of normal), HbA1c would have picked up 87.1% of patients with GDM.CONCLUSIONS:This study suggests that HbA1c is a reasonably sensitive screening measure of GDM in this high-risk population. Acknowledging limitations resulting from the study design, further prospective studies are warranted to verify this conclusion, and to evaluate the specificity of HbA1c as a screening test for GDM.