Estimation of Glycated Hemoglobin A (HbA1c) at time of Pregnancy Diagnosis as a discriminative Early test for Women vulnerable to develop Gestational Diabetes Mellitus at the 24th Gestational Week

Aim: Estimation of blood glycated hemoglobin A (HbA1c) level in newly pregnant women at time of pregnancy diagnosis (T0) and 3-monthly thereafter to detect any relation between these levels and the change in maternal blood glucose (BG) levels during pregnancy. Material and Methods: 304 newly pregnant women gave fasting blood samples for estimation of T0 HbA1c level and then underwent the 75-Oral glucose tolerance test (OGTT) and were asked to re-attend the clinic overnight fasting at the start of the 12th and at the 24th-28th gestational week (GW) for estimation of HbA1c levels and to repeat the 75-OGTT. ΔHbA1c was calculated as the difference between HbA1c levels estimated at 12th GW minus T0 levels. The results of the 75-OGTT were interpreted for diagnosis of gestational diabetes mellitus (GDM) and HbA1c at range of 4-6% indicates non-diabetic state. Study outcome is the ability of T0 levels of HbA1c to discriminate women vulnerable to develop GDM around the 24th to the 28th GW. Results: 38 women developed GDM, while 286 women completed their pregnancy free of GDM. GDM women had significantly higher T0 body mass index (BMI) and HbA1c levels than Non-GDM women. Moreover, the 12th and 24th GW HbA1c levels and ΔHbA1c were significantly higher in GDM women. The 24th GW 2hr-postprandial BG (PPBG) levels showed significant positive correlation with T0 BMI, fasting BG and 2hr-PPBG and with T0 and 12th GW levels of HbA1c and ΔHbA1c. Regression analysis defined T0 level of HbA1c, ΔHbA1c, 12th GW HbA1c level and T0 BMI as the significant positive predictor for the 24th GW 2hr-PPBG level. ROC curve analysis defined T0 level of HbA1c and ΔHbA1c as the significant predictors for the 24th GW 2hr-PPBG level which is diagnostic for GDM. Conclusion: Development and severity of GDM could be predicted at time of pregnancy diagnosis by high HbA1c level and assured by calculation of the extent of change in HbA1c level at the 12th GW.