ABSTRACT
OBJECTIVE: To determine the effect of lowering the cutoff values of 3-hour oral glucose tolerance test (OGTT) for gestational diabetes mellitus (GDM). METHODS: Patients with an abnormal 50 gm glucose challenge test (GCT) of more than 130 mg/dL at 24-28 weeks of gestation underwent a 3-hour OGTT at 28-32 weeks of gestation. Patients were divided into four groups according to the criteria recommended by Carpenter-Coustan or National Diabetes Data Group (NDDG) (Control: 50 gm GCT negative [n=268], Borderline: 2 or more abnormal values met or exceeded Carpenter-Coustan criteria but not the NDDG criteria [n=100], NDDG I: 2 or more abnormal values met or exceeded NDDG criteria, [treated, n=70], NDDG II: [not treated, n=42]). Obstetric and perinatal outcomes were analyzed retrospectively. RESULTS: Of 5,827 pregnant women screened for GDM, 112 (1.9%) met the NDDG criteria, whereas 212 (3.6%) met the Carpenter-Coustan criteria. The incidences of poor maternal outcomes were 20.1%, 28.0%, 47.1%, 21.4%, and the incidences of poor neonatal outcomes were 3.7%, 6.0%, 14.3%, 16.7% in the four groups (p<0.05). Multivariable logistic regression analysis showed that 1) NDDG I showed an independent risk factor for poor maternal outcome (OR, 3.37), but the borderline group did not, 2) NDDG I showed an independent risk factor for poor neonatal outcome (OR, 3.87), but the borderline group did not, 3) the borderline group showed an independent risk factor for preterm delivery (OR, 2.67). CONCLUSION: Lowering the cutoff values would increase the number of pregnant women with GDM, while only minimally affecting the perinatal outcomes. Further large-scale prospective studies for Korean pregnant women may be needed.