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. 2025 Mar 31;25(1):374.
doi: 10.1186/s12884-025-07389-3.

Utility of maternal A1c measurement in the second trimester for the diagnosis of gestational diabetes mellitus

Affiliations

Utility of maternal A1c measurement in the second trimester for the diagnosis of gestational diabetes mellitus

Neval Cayonu Kahraman et al. BMC Pregnancy Childbirth. .

Abstract

Background: To investigate the effectiveness of maternal hemoglobin A1c (HbA1c) in the diagnosis of gestational diabetes mellitus (GDM) in the second trimester.

Methods: A total of 3000 pregnant women between 24 and 28 weeks of gestation were included in the study. Screening for gestational diabetes was performed using maternal HbA1c in 1200 pregnant women who either refused or could not tolerate the OGTT. The HbA1c value for the diagnosis of GDM was set at ≥ 5.7% in accordance with a meta-analysis by Paula B. Renz et al. A total of 154 pregnant women with HbA1c ≥ 5.7% were diagnosed with gestational diabetes, and their data were recorded prospectively. These data were compared with obstetric outcomes in 250 pregnant women diagnosed with diabetes by performing a 100-g OGTT after a 50-g glucose challenge test (GCT).

Results: There were no significant differences between two groups in terms of maternal age, gestational age at diagnosis, gravidity, and parity. Body mass index (BMI) was found to be significantly higher in pregnant women with HbA1c levels ≥ 5.7% (p < 0.001). Polyhydramnios was more common in the HbA1c ≥ 5.7% group and oligohydramnios was more common in the OGTT group (p < 0.001). Neonatal hypoglycemia was found to be significantly higher in the OGTT group (p < 0.05). The median HbA1c value were different in each group (OGTT group 5.6%, HbA1c group 5.8%; p < 0.001).

Conclusion: HbA1c testing has lower accuracy rates than OGTT in diagnosing GDM because it may miss diagnosis in some groups.

Keywords: Gestational diabetes mellitus; HbA1c; Oral glucose tolerance test; Poor obstetric outcome.

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Conflict of interest statement

Declarations. Ethics approval and consent to participate: Ethical approval was obtained by the institutional review board from Ankara Etlik Zubeyde Hanım Women's Health Training and Research Hospital on . The study complied with the ethical principles for medical research of the Declaration of Helsinki 09.06.2021 # 2021/63. Consent for publication: Not applicable. Informed consent: A verbal and written informed consent was obtained from all participants. Competing interests: The authors declare no competing interests.

Figures

Fig. 1
Fig. 1
Flowchart of GDM diagnosis. Abbreviations: GDM: Gestational diabetes mellitus, GCT: Glucose challenge test, OGTT: Oral glucose tolerance test, HbA1c: Hemoglobin A1c

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