Role of HbA1c in diagnosis of gestational diabetes mellitus.

OBJECTIVE: To evaluate glycated haemoglobin as a biomarker for diagnosing gestational diabetes mellitus while keeping the oral glucose tolerance test as the gold standard. METHODS: The cross-sectional study was conducted from Januray, 2016, to January, 2018, at PNS Hafeez Hospital, Islamabad, Pakistan and comprised of pregnant subjects who were first subjected to 2-hour oral glucose tolerance test along with the first evaluation of glycated haemoglobin. Clinical evaluation, including history and measurements of anthropometric indices and blood pressure, were also done. On the basis of the results, the subjects were grouped as those having gestational diabetes mellitus (group A) and those without it (group B). Data was analysed using SPSS 15. RESULTS: Of the 280 subjects, gestational diabetes mellitus was found in 50(17.85%). Differences in glycated haemoglobin between the groups was significant (p<0.002). Glycated haemoglobin test provided sensitivity of 70% and specificity of 84.78%. CONCLUSIONS: With due adjustments, glycated haemoglobin testing can help in reducing the frequency of oral glucose tolerance test.

Glucose Tolerance versus HbA1c Results as Depictive of Gestational Diabetes Mellitus.

OBJECTIVE: To evaluate glucose tolerance patterns in pregnant ladies undergoing 2-hour oral glucose tolerance test (OGTT) for comparing fasting, 1-hour, 2-hour post-glucose load results, HbA1c, sum of all glucose readings with and without gestational diabetes mellitus (GDM) using International Association of the Diabetes and Pregnancy Study Group (IADPSG) diagnostic criteria. STUDY DESIGN: Cross-sectional analysis. PLACE AND DURATION OF STUDY: PNS Hafeez, Naval Hospital, Islamabad, from January 2016 to July 2017. METHODOLOGY: For 280 evaluated subjects reporting in mid-pregnancy for OGTT, results were segregated into four groups based upon comparison of 2-hour glucose result with 1-hour glucose. Group-1 2-hour results drop being >2.0 mmol/L than1-hour results, group-2 with 2-hour result between <2.0 to >0.5 mmol/L than peak at 1-hour, and group-3 with either 2-hour glucose drop being <0.5mmol/L or >1-hour results. Further, the ROC curve analysis was performed to compare the AUC for fasting plasma glucose, 1-hour post OGTT result, 2-hour post-OGTT result, factor additive of all OGTT readings and HbA1c. RESULTS: There was a progressive rise in HbA1c from group-1 to group-3 (p<0.001). Area under curve (AUC) for various diagnostic parameters for diagnosing GDM for additive value of all glucose results was 0.962 (95% CI: 0.935-0.988), 0.881 (95% CI: 0.818-0944) for plasma glucose at 2-hour, for plasma glucose at 1-hour 0.898 (95% CI: 0.0.842-0.954), 0.831 (95% CI: 0.0.762-0.901) for fasting plasma glucose and 0.668 (95% CI: 0.0.578-0.759) for HbA1c (p<0.001). CONCLUSION: Pregnant ladies demonstrating poor tolerance to glucose at 2-hour were observed to have higher HbA1c levels.