Background: The best method of screening for gestational diabetes (GDM) remains unsettled. The 50-g glucose challenge test (GCT) is used in a two-stage screening process but its best threshold value can vary according to population.
Aims: To evaluate the role of risk factors in conjunction with GCT and to determine an appropriate threshold for the one-hour venous plasma glucose with the GCT.
Method: In a prospective study, 1600 women at antenatal booking without a history of diabetes mellitus or GDM filled a form on risk factors before GCT. Women who had GCT >or= 7.2 mmol/L underwent the 75-g oral glucose tolerance test (OGTT). GDM was diagnosed according to WHO (1999) criteria.
Result: Thirty-five per cent had GCT >or= 7.2 mmol/L, 32.6% underwent OGTT and 34.5% of OGTT confirmed GDM. The GDM rate in our population was at least 11.4%. Examination of the receiver operator characteristic curve suggested that the best threshold value for the GCT in our population was >or= 7.6 mmol/L. Multivariable logistic regression demonstrated that only GCT >or= 7.6 mmol/L was an independent predictor for GDM (adjusted odds ratio 3.7: P < 0.001). After GCT, maternal age and anthropometry, OGTT during the third trimester, family history, obstetric history and glycosuria were not independent predictors of GDM.
Conclusions: Risk factors were not independent predictors of GDM in women with GCT >or= 7.2 mmol/L. GCT threshold value >or= 7.6 mmol is appropriate for the Malaysian population at high risk of GDM.
OBJECTIVE:
To evaluate the 50-g glucose challenge test (GCT) on pregnancy outcome in a multiethnic Asian population at high risk for gestational diabetes (GDM).
METHODS:
GCT was positive if the 1-hour plasma glucose level was >or=7.2 mmol/L. GDM was diagnosed by a 75-g glucose tolerance test using WHO (1999) criteria. Of the 1368 women enrolled in the study, 892 were GCT negative, 308 were GCT false-positive, and 168 had GDM. Pregnancy outcomes were extracted from hospital records. Multivariable logistic regression analysis was performed with GCT negative women as the reference group.
RESULTS:
GCT false-positive status was associated with preterm birth (adjusted odds ratio [AOR] 2.1; 95% CI, 1.2-3.7) and postpartum hemorrhage (AOR 1.7; 95% CI, 1.0-2.7). GDM was associated with labor induction (AOR 5.0; 95% CI, 3.3-7.5), cesarean delivery (AOR 2.2; 95% CI, 1.6-3.2), postpartum hemorrhage (AOR 2.1; 95% CI, 1.2-3.7), and neonatal macrosomia (AOR 2.5; 95% CI, 1.0-6.0).
CONCLUSION:
GCT false-positive women had an increased likelihood of an adverse pregnancy outcome. The role and threshold of the GCT needs re-evaluation.