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.