Hemoglobin A1c as a Substitute for Oral Glucose Testing in Early Pregnancy Screening.

 Current recommendations for individuals with risk factors for gestational diabetes mellitus (GDM) call for screening in early pregnancy. However, there is currently no clear consensus on a specific screening modality. This study evaluates whether a hemoglobin A1c (HbA1c) screening in individuals with risk factors for gestational diabetes (GDM) could be used instead of an early 1-hour glucose challenge test (GCT). We hypothesized that the HbA1c could replace 1-hour GCT in early pregnancy evaluation STUDY DESIGN:  This is a prospective observational trial at a single tertiary referral center of women with at least one risk factor for GDM who were screened at 16 weeks of gestation with both 1-hour GCT or HbA1c. Exclusion criteria include: previous diagnosis of diabetes mellitus, multiple gestation, miscarriage, or missing delivery information. The diagnosis of GDM was made by a 3-hour 100-g glucose tolerance test, using the Carpenter-Coustan criteria (at least two results >94, 179, 154, and 139 mg/dL for fasting, 1-, 2-, and 3-hour values, respectively), 1-hour GCT > 200 mg/dL, or HbA1c > 6.5%.