Gestational Diabetes: Comparison of Random and Fasting Plasma Glucose as Modalities of Screening

Abstract

Objective: Gestational diabetes is glucose intolerance of varying severity with onset in the index pregnancy. This study aimed to compare fasting plasma glucose (FPG) with random plasma glucose (RPG) among pregnant females as methods of screening for gestational diabetes. Methods: A cross-sectional study of 100 pregnant females selected to have screening for gestational diabetes between gestational ages of 24 and 28 weeks using RPG and FPG. All the subjects had 75 g oral glucose tolerance test as the gold standard. Venous plasma glucose assay was performed using glucose oxidase method. Results: The prevalence of gestational diabetes was 29% using FPG cut-off ≥5.1 mmol/L and 6% using RPG cut-off ≥7.8 mmol/L. The RPG cut-off ≥11.1 mmol/L gave the lowest prevalence rate of 2%, while 75 g oral glucose tolerance test (gold standard test) gave the highest prevalence rate of 30%. RPG cut-off ≥7.8 mmol/L revealed a positive-predictive value of 66.7%, negative-predictive value of 72.3%, and area under the curve of 0.845 compared with FPG level at threshold of 5.1 mmol/L, which gave positive-predictive value of 93.1%, negative-predictive value of 95.8%, and area under the curve 0.920. Conclusion: This study revealed that FPG threshold of 5.1 mmol/L alone performed excellently as a screening test.