Hemoglobin A1c as a predictor of gestational diabetes mellitus in pregnancy less than 20 weeks of gestation-a prospective observational study

Abstract

Background: Glycosylated HbA1c is currently a good measure to know sugar control in non-pregnant patients. This study aimed to comprehensively examine the values of HbA1c in the first 20 weeks of pregnancy and its relationship with GDM.

Objectives: (i) To study the Utility of Glycosylated Haemoglobin as a screening tool/predictor of Gestational Diabetes Mellitus In less than 20 weeks of Pregnancy. (ii) To evaluate the usefulness of HbA1c as a prognostic indicator of pregnancy outcome.

Methods: This prospective observational study was conducted in the Department of Gynaecology and Obstetrics, SKIMS Medical College and Hospital, Srinagar over a period of two years. A total number of 100 Patients enrolled in the study group underwent HbA1c measurements besides all the routine investigations on their first booking visit at less than 20 weeks of pregnancy. On follow up at 24-28 weeks the patients in the study group underwent 75-g OGTT and the results were correlated.

Results: Optimal cut-off value for HbA1c was 5.6% with a sensitivity of 82.3% and specificity of 69.8%.The mean BMI of the patients with HbA1c ≤ 5.6 was 23.1±2.37 kg/m2 and HbA1c > 5.6 was 25.4±2.52 kg/m2 which was statistically significant with a p-value of < 0.001. 35.9% of the patients with HbA1c > 5.6% developed GDM, whereas only 4.9% of the patients with HbA1c ≤ 5.6 had GDM. In our study, the mean HbA1c in the GDM group was 5.73±0.326 and in the non-GDM, it was 5.18±0.629 with a P-value of 0.0008. The association between HbA1c level at less than 20 weeks of gestation and GDM was significant. Mode of delivery had no significant association with HbA1c levels. 56.4% of the patients with HbA1c >5.65 and 42.6% of patients with HbA1c ≤5.6% underwent LSCS. The mean birth weight of neonates born to mothers with HbA1c > 5.6 was 3.6+0.448kgs which was a statistically significant finding in this study. Apgar score at 1 and 5 minutes has a significant association with HbA1c levels. Respiratory distress syndrome and neonatal hypoglycaemia developed in 33.3% and 12.8% of the neonates born to mothers with HbA1c > 5.6% respectively, with RDS being the most common complication associated.

Conclusion: The HbA1c level in pregnant patients at less than 20 weeks of pregnancy may be helpful as a screening tool and a prognostic biomarker for adverse pregnancy outcomes.