Study design and subjects
This retrospective cohort study included 2,789 pregnant women who delivered at Gangnam CHA Medical Center (Seoul, Korea) between July 1, 2007, and December 31, 2009. Those with twin pregnancy, fetal anomaly, hypertensive disorder before pregnancy, diabetes, and missing pre-pregnancy or delivery weights were excluded. Among these participants, we analyzed 1,058 pregnant women who completed the 100-g OGTT after a 50-g glucose challenge test between 24 and 28 weeks of gestation. Routine prenatal examinations, including maternal body weight, blood pressure, and fetal crown-rump length, were performed at 11, 16, 26, and 35 gestational weeks at obstetrics outpatient clinics. Blood tests, including hemoglobin, fasting glucose, lipid profile, C-peptide, and insulin, were conducted at 26 gestational weeks. Based on the American Diabetes Association guidelines, 16target glucose levels were as follows: fasting glucose <95 mg/dL, 1-h postprandial glucose <140 mg/dL, and 2-h postprandial glucose <120 mg/dL. Of the 257 patients with GDM, 18 received insulin treatment to achieve the target blood glucose level. This study was approved by the Institutional Review Board of Gangnam CHA Medical Center (IRB No. KNC 10-025). Informed consent was waived because all the patient data were anonymized and de-identified. The detailed protocol has been previously published. 17,18
A 100-g OGTT was conducted in pregnant women who met the diagnostic criteria of 50-g oral glucose challenge tests, which is a 1-h glucose level ≥130 mg/dL, between 24 and 28 weeks of gestation. We defined GDM as two or more of the following positive results in a 3-h 100-g OGTT after an overnight fast of at least 8 h, but no more than 14 h: fasting, ≥95 mg/dL; 1 h, ≥180 mg/dL; 2 h, ≥155 mg/dL; and 3 h, ≥140 mg/dL.5