RESUMO
OBJECTIVE: To evaluate the cutoff value of the 50 grams glucose challenge test (GCT) for screening of gestational diabetes mellitus (GDM) in each trimester in potential diabetic pregnancy and to determine the prevalence of GDM. STUDY DESIGN: Retrospective descriptive study (Diagnostic test). SETTING: Section of Obstetrics and Gynecology, Taksin Hospital. SUBJECTS: Two thousand and ten potential diabetic pregnant women who attended the antenatal care clinic at Taksin Hospital between August 2004 and December 2005 were identified and recruited based on risk indicators. MATERIAL AND METHOD: A GCT was performed If GCT was positive, 100 grams oral glucose tolerance test (OGTT) was done to confirm the GDM. All relevant data including demographic information, GCT and OGTT results were collected The receiver operating characteristic (ROC) curve was used to identify the cutoff value of GCT for screening of GDM. MAIN OUTCOME MEASURES: The cutoff value of GCT for screening of GDM in each trimester by using ROC curve. RESULTS: The cutoff values of GCT in 1st, 2nd, 3rd, and all trimesters were 179, 177, 184, and 179 mg/dl respectively The authors recommended 177 mg/dl as the cutoff value of GCT for screening of GDM in potential diabetic pregnancy in each trimester The prevalence of GDM in 1st, 2nd, 3rd, and all trimesters were 14.22, 13.04, 11.96, and 13.2% respectively. CONCLUSION: The threshold of 177 mg/dl was recommended as the cutoff value of GCT for screening of GDM in each trimester in potential diabetic pregnancy. The prevalence was 13.2%.