First trimester glycosylated hemoglobin for gestational diabetes mellitus screening

Our aim in this study is to evaluate the efficacy of HbA1c in screening for GDM during the first trimester of pregnancy.

In this retrospective cohort study, we evaluated the first trimester HbA1c (ft-HbA1c) levels of 195 pregnant women who attended our university hospital's obstetrics clinic. Blood samples were drawn from patients during 11-14 weeks of gestation. After that, all patients were screened using standardized one-step 75gr OGTT between 24 and 28 weeks of pregnancy.

In this study, 195 pregnant women were included. Thirty-two (16.4%) of the women included in this study were diagnosed with GDM. The mean ft-HbA1c level was 5.52% in those who developed GDM and 5.21% in those who did not develop GDM (p = 0.000). Only seven (3.6%) of the women included in this study had an ft-HbA1c level above the prediabetes limit of 5.7%. All these women with prediabetes developed GDM. The cut-off value for ft-HbA1c to distinguish GDM was 5,33%. For this cut-off value, the sensitivity was 71.9%, and the specificity was 82.8%.

The findings suggest that ft-HbA1c level is a promising biomarker for GDM screening. Especially, patients with ft-HbA1c level ≥5.33% are at increased risk for developing GDM.