VP47.06: Determination of relationship between HbA1C levels and early diagnosis of gestational diabetes

Abstract

Gestational diabetes mellitus (GDM) is associated with undesirable complications on the mother and newborn. Screening test for GDM is currently performed between 24-28 weeks of pregnancy. However, 30-50% of cases with type 2 diabetes remain undiagnosed during pregnancy. International Association of Diabetes and Pregnancy Study Groups, America Diabetes Association and World Health Organization recommend diabetes screening in pregnancy at the first visit for the pregnant women. However, the most appropriate test and its threshold are not yet clear. The HbA1C level seems an appropriate criterion for this screening test. Therefore, this study aimed to determine HbA1C levels in the first trimester of pregnancy for the diagnosis of GDM in high risk women referred to Ahvaz Imam Hospital. Total of 158 singleton pregnant women, in their gestational age less than 20 weeks, who were not the diagnosed cases of diabetes and referred for prenatal care participated in the study. A questionnaire consisting of clinical and demographic information such as maternal age, gestational age at the time of blood sample receipt, BMI, gestational diabetes history, and the number of previous pregnancy was filled for each patient. Blood sample of these women was taken once in gestational age less than 20 weeks after 12 hours of fasting, fasting blood sample, one-hour and two hours after ingestion of 75 g glucose, and HbA1c level was determined. Participants with HbA1c >= 6.5 or FBS >=126 or sugar random sample >= 200 were diagnosed as diabetes before pregnancy and were excluded from the study. The test was repeated for those who entered the study in gestational ages 24-28 weeks. The results showed that average HbA1C level in pregnant mothers whose GDM has been diagnosed before 20th week of pregnancy is more than their counterparts whose GDM had not been diagnosed before 20th week of pregnancy (P= 0.02). HbA1C cut point for the diagnosis of GDM before 20th week of pregnancy was obtained 5.550. Also HbA1C level average in pregnant mothers whose GDM was diagnosed in 24-28 weeks is higher than HbA1C levels in pregnant mothers whose glucose tolerance test was negative in 24-28 weeks (P= 0.005). The specificity of the GTT 75 g glucose for GDM diagnosis before 20 weeks of pregnancy was relatively poor. The results also showed sensitivity, specificity, positive predictive value, and negative predictive value of 100%, 86.6%, 75.4%, and 100%, respectively. The findings showed that BMI variable is significantly effective on HbA1C changes in the diagnosis of GDM before 20 weeks of pregnancy (P< 0.0001).