The utility of HbA1c for screening gestational diabetes mellitus and its relationship with adverse pregnancy outcomes

Abstract

Aims: To evaluate the utility of glycated hemoglobin A1c (HbA1c) for screening gestational diabetes mellitus (GDM) and analyze its association with adverse pregnancy outcomes in a cohort of pregnant women.

Methods: Women with singleton pregnancies, who completed a 2h oral glucose tolerance test (OGTT) and HbA1c test at gestational week 24-28 were enrolled in this retrospective study. Clinical information was obtained and statistical analyses were performed to assess the diagnostic value of HbA1c for GDM and the association of HbA1c with adverse pregnancy outcomes.

Results: Of the 1959 pregnant women enrolled in the study, 413 were diagnosed with GDM. A HbA1c cutoff value <4.8% (29mmol/mol) showed adequate sensitivity to exclude GDM (85.0%) but low specificity (31.8%). While HbA1c cutoff value ≥5.5% (37mmol/mol) presented adequate specificity (95.7%) but low sensitivity (14.8%) in diagnosing GDM. Adoption of HbA1c as a screening test for GDM could eliminate the need for an OGTT in 34.7% women in our study, however, with 6.5% being wrongly diagnosed. HbA1c level was significantly associated with the risk of preterm delivery, neonatal hyperbilirubinemia, and neonatal asphyxia.

Conclusions: Whether adoption of HbA1c as a screening test for GDM would benefit pregnant women remains to be determined. However, HbA1c might be a useful tool to predict patients at increased risk of several adverse pregnancy outcomes.

Keywords: Adverse pregnancy outcomes; Gestational diabetes mellitus; Glycated haemoglobin A1c; OGTT.