Background and Objectives Recently, the use of the hemoglobin A1C test as a predictor of gestational diabetes has been investigated, yielding varying results. This study was designed to establish a cut-off point for hemoglobin A1C and evaluate its effectiveness in predicting gestational diabetes before the 20th week of pregnancy.
Subjects and Methods This was a cross-sectional study conducted on 300 pregnant women in Zahedan in 2023. For all pregnant women, the hemoglobin A1C level was measured at the beginning of the study, and the OGTT test was performed in the 24th to 28th week of pregnancy. The data obtained from this study were analyzed using SPSS software. According to the normal or abnormal results of HbA1C and OGTT, sensitivity (the ability of the test to correctly diagnose all involved cases), specificity (the ability of the test to correctly diagnose all normal cases), the positive predictive value, and the negative predictive value of the HbA1C test were calculated. In order to find the diagnostic cut-off point of HbA1C in predicting gestational diabetes, OGTT was used as the golden diagnostic test in the ROC curve. The significance level in this study was set at 5%.
Results The average age of the study participants was 27.56 ± 5.49 years. Of the pregnant women included in the study, 101 (33.7%) were diagnosed with gestational diabetes. In this study, the ROC curve analysis showed that the area under the curve was 0.85 (95% confidence interval, 82-89). Also, based on ROC analysis, hemoglobin A1C with a cutoff point of 5.6% had a sensitivity of 71.3%, a specificity of 94%, a positive predictive value of 88%, and a negative predictive value of 86%..
Conclusion  Performing a hemoglobin A1C test during the first trimester of pregnancy is a highly sensitive and specific method for predicting gestational diabetes.