This study sought to compare test characteristics of hemoglobin A1c, oral glucose tolerance test and fasting plasma glucose for the development of gestational diabetes among women with prediabetes. Diabetes outcomes were compared by screening test used for prediabetes diagnosis among a retrospective cohort of pregnant patients between 2017-2021. During the study, 8132 patients received diabetes screening and 14.0% met criteria for prediabetes. By screening test, 75.1% were screened with hemoglobin A1c, 10.0% with fasting plasma glucose and 14.9% with a 75-g oral glucose tolerance test. Hemoglobin A1c had the highest positive predictive value (67.2%). Use of hemoglobin A1c was significantly more likely to identify women with GDM than oral glucose tolerance test (aOR 3.94, 95% CI 2.30-6.73). In this study cohort, hemoglobin A1c was able to identify patients that were more likely to develop GDM in an at-risk population.IMPACT STATEMENTWhat is already known on this subject? Prediabetes is becoming more common in the general population; however little is known about prediabetes in pregnancy. Women with prediabetes in pregnancy appear to be at increased risk of developing gestational diabetes mellitus, however there is minimal information about various screening tests performance in pregnancy for detection of prediabetes and subsequent gestational diabetes.What do the results of this study add? The results of this study compare three commonly used screening tests for screening for diabetes. When identifying women with prediabetes, they are at increased risk for developing gestational diabetes mellitus if identified by hemoglobin A1c.What are the implications of these findings for clinical practice and/or further research? The clinical implication of this study is that women can be screened with hemoglobin A1c in early pregnancy for both overt diabetes, but also may be identified as high risk with prediabetes. Among women with prediabetes by hemoglobin A1c, they remain at high risk for developing gestational diabetes mellitus.
Keywords: Prediabetes; diabetes screening; hemoglobin A1c; perinatal outcomes; pregnancy.