50-Grams Glucose Challenge Test for Screening of Gestational Diabetes Mellitus in High Risk Pregnancy
Waraporn Juntarat MD*, Wibool Rueangchainikhom MD*, Sinat Promas MD*
Affiliation : * Department of Obstetrics and Gynecology, Bhumibol Adulyadej Hospital
Objective : To evaluate the cutoff value of the 1-hr, 50-gram glucose challenge test (GCT) for screening of
gestational diabetes mellitus (GDM), in high-risk pregnancy, and to determine the prevalence of GDM in this
group.
Study
Design : Descriptive study (Diagnostic test).
Subjects : Eight hundred and thirty-eight pregnant women, 24-28 weeks, were identified and recruited based
on risk indicators between January and October 2004.
Materials and Methods : A GCT was performed in this group. All women with plasma glucose value > 130 mg/
dl were given a 3-hr, 100-gram glucose tolerance test (OGTT) to diagnose gestational diabetes mellitus using
Carpenter and Coustan diagnostic criteria. The receiver-operator characteristic (ROC) curve was used to
identify the cut-off value of GCT for detecting GDM.
Main outcome measures: The cut-off value of GCT for detecting GDM by using ROC curve with the sensitivity
and specificity of various cut-off values.
Results : The ROC curve identified a GCT value of > 140 mg/dl as the cut-off value for detecting GDM, which
showed the sensitivity and specificity of 95.3% and 48.6% respectively. The prevalence of GDM in high-risk
pregnant women was 20.17% (169/838).
Conclusions : Recommended threshold of 140 mg/dl used as the cut-off value of 50-gram, 1-hr GCT for screen-
ing GDM in high-risk pregnancy.
Keywords : 1 hr; 50 gram glucose challenge test, Screening of gestational diabetes mellitus, High-risk preg- nancy
