661: Gestational diabetes mellitus: Comparison of random and fasting plasma glucose as modalities of screening

Abstract

To compare fasting plasma glucose (FPG) with random plasma glucose (RPG) among pregnant women as methods of screening for gestational diabetes mellitus A comparative cross-sectional study of 100 pregnant women who were selected to have screening for GDM done betwwen gestational ages of 24 to 28 weeks using random plasma glucose and fasting plasma glucose. All the subjects had 75g oral glucose tolerance test as the gold standard. Venous plasma glucose assay was performed using glucose oxidase method. During this study, a total of 100 eligible pregnant women were screened for GDM using FPG, RPG and the 75g -OGTT. The mean age±standard deviation (sd) of the participants was 34.81±4.04 yrs; mean BMI was 31.46±7.29 kg/m2 and mean parity was 1.38±1.15 (Table I). The mean RPG of the participants was 5.53±1.57 mmol/L while the mean FPG was 4.70±1.02 mmol/L. The prevalence of GDM was 29% using FPG cut off≥ 5.1 mmol/L; 16% using FPG cut off≥5.3 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 75g-OGTT (Gold standard test) gave the highest prevalence rate of 30%. The primary outcome was measured as the accuracy of GDM screening using RPG which revealed sensitivity of 13.8%, specificity of 97.1%, positive predictive value of 66.7% and negative predictive value of 72.3% as compared with FPG threshold of 5.1 mmol/L which gave sensitivity of 90%, specificity of 97.1%, PPV of 93.1% and NPV of 95.8%. The receiver operating characteristics curve (ROC) plotted for both screening tets gave AUC of 0.845 for RPG and 0.920 for FPG. The findings from this study reveal that FPG threshold of 5.1 mmol/L has a high sensitivity of 90% and specificity of 97.1% as well as AUC of 0.920, which is excellent for a screening test. The use of RPG threshold of 7.8 mmol/L gave sensitivity of 13.8% and specificity of 97.1% with an AUC of 0.845 which was inferior to FPG.View Large Image Figure ViewerDownload Hi-res image Download (PPT)