Assessment of Diagnostic Accuracy of Early OGTT in Prediction of GDM taking 2nd Trimester OGTT as Gold Standard

Abstract

Background: Early diagnosis of gestational diabetes may have the potential to improve maternal and neonatal health outcomes.

Objective: To determine the diagnostic accuracy of early OGTT in the prediction of Gestational Diabetes Mellitus by taking 2nd-trimester OGTT as a gold standard.

Methods: This was a cross-sectional study that enrolled 420 pregnant women with single pregnancy between 18 and 40 years of age, who had their first prenatal visit in PAF hospital at 1^st or early 2^nd trimester, from 1^st August 2022 to 31^st January 2023. All the women in their first trimester were subjected to 75g OGTT and the values of the plasma glucose concentration were recorded at fasting level, after 1-hr and after 2-hrs respectively. All these results were compared with 2^nd-trimester OGTT of the same patients taking 2^nd-trimester OGTT as a gold standard.

Results: The mean age of the women was 27±4 years. The mean BSF and 2-hr plasma glucose of women in 1^st OGTT were 4.74±0.36 mmol/L and 6.58±0.63 mmol/L respectively. The mean BSF and 2-hr plasma glucose of women in 2^nd OGTT were 4.89±0.32 mmol/L and 6.04±0.97 mmol/L respectively. The prevalence of GDM in 1^st OGTT was 6.4% and in 2^nd OGTT it was 20.5%. The sensitivity, specificity, PPV, and NPV of the 1^st OGTT performed between 10 to 17 weeks of gestation were found as 26.7%, 98.8%, 85.18%, and 83.97% respectively.

Conclusion: The early OGTT performed during 10-17 weeks of gestation has good specificity, with good positive predictive and negative predictive values but poor sensitivity, taking the late 2^nd-trimester OGTT as a gold standard.