American College of Obstetricians and Gynecologists (ACOG) recommends gestational diabetes mellitus (GDM) testing using a 1-hour 50-gram oral glucose challenge test (24 to 28 weeks gestation) and if elevated (>140mg/dl), a 3-hour 100-gram oral glucose tolerance test. Objective: To determine if hemoglobin A1c (HbA1c) testing can replace ACOG guidelines, offering a more tolerable, less time-consuming test for GDM. Methods: This is a prospective cohort study of patients presenting at ≤14 weeks

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... ation for prenatal care between 11/2011 and 6/2014. HbA1c levels obtained at initial visit and 24 to 28 weeks gestation were compared among patients with and without GDM and tested as a replacement for ACOG guidelines. Results: Study was comprised of 146 of 364 patients meeting inclusion criteria. Mean age was 25 years, 41.5% met criteria for obesity, and 50% had a famly history of diabetes mellitus (DM). The rate of GDM was 8.2% (12/146.) There was a significant difference in the 24 to 28 week HbA1c test between GDM patients (5.3 ± 0.4) and non GDM patients (5.0 ± 0.3; p=0.028) Initial HbA1c values at ≤14 weeks were compared to HbA1c at 24 to 28 weeks. Findings revealed a small, but significant decrease in HbA1c (5.2% vs 5.1%, p<0.001). However, initial mean HbA1c levels were higher in patients with GDM compared to patients without GDM (5.3% vs 5.1%, p=0.027). Elevated HbA1c (>5.5%) and positive testing for GDM showed significant, but weak agreement (Kappa=0.69, p=0.041), [sensitivity: 25% and specificity: 92.5%]. Receiver Operator Curve (ROC) analysis determined optimal threshold of HbA1c of 5.15% yielding sensitivity of 66.7%; a specificity of 66.4%, PPV of 15.1%, and NPV of 95.7%. Analysis of mean change from initial HbA1c ≤14 weeks compared to HbA1c at 24 to 28 weeks resulted in no main effect for GDM, but a significant GDM by HbA1c interaction (p=0.002). GDM patients demonstrated increased mean HbA1c at ≤24 to 28 weeks and non-diabetics decreased mean HbA1c at 24 to 28 weeks gestation. Conclusion: While our data showed that patients with GDM had elevated levels of HbA1c at 24 to 28 weeks gestation, this test is not a reliable replacement for ACOG guidelines with oral glucose challenge testing (OGCT). Schaible B (2018) Hemoglobin A1c as a screening strategy for gestational diabetes Med Dent Res, 2018