Objective To investigate whether area under the curve (AUC) of oral glucose tolerance test (OGTT) could work as a predictor of outcomes of gestational diabetes mellitus (GDM) on condition that blood glucose is controlled. Methods A total of 1 796 women who had a standard antenatal care in Peking University First Hospital and gave single live births from July 1, 2011 to December 31,2 013 were included.They should be diagnosed of GDM by the diagnosis criteria of gestational diabetes published by the Ministry of Health of PRC and diabetes pre-pregnancy excluded. Data were analyzed with SPSS 17.0, grouping by AUC. Results (1)Women with higher AUC had a rising trend of age and a downward trend of gestational weight gain, however, not statistically significant [specifically, in the four group of less than 15.00 mmol·L-1·h-1, 15.00 to 16.79 mmol · L-1 · h-1, 16.80 to 17.99 mmol · L-1 · h-1 and 18.00 mmol · L-1 · h-1 or more, gestational weight gain was (15.3±5.2), (14.1±4.8), (13.5±4.7) and (13.1±4.8) kg]. The prevalence of macrosomia raised while AUC increased. Those with an AUC of lower than 15.00 (mmol·L-1·h-1) had a lower risk of macrosomia (P=0.04) . But those with an AUC of 18.00 (mmol·L-1·h-1) or more had a higher risk of macrosomia (P=0.02). There was a rising trend in premature birth and preeclampsia with AUC increasing but not significant (the prevalence of premature birth was 4.38%, 5.36%, 7.71%and 7.94%while that of preeclampsia was 2.85%, 4.69%, 4.67% and 5.08% in these four groups).(2)The prevalence of macrosomia was 12.76% (54/423) when overweight pre-pregnancy ,significantly higher compared with 5.87%(65/1 107) in normal group. The prevalence of preeclampsia was 5.91%(25/423) and 3.34%(37/1 107) in those two groups, which was also significantly different. The obese group had a statistically highest prevalence of preeclampsia of 9.23%(12/130). (3)AUC (P<0.05, OR=1.113, 95%CI:1.008-1.218), as well as gestational weight gain (P<0.05, OR=1.520, 95%CI:1.279-1.806) and pre-pregnancy BMI (P<0.05, OR=1.183, 95%CI:1.125-1.243) made a difference in the prevalence of macrosomia. Meanwhile, pre-pregnancy BMI made sense in the prevalence of premature labor (P<0.05, OR=1.059, 95%CI:1.003-1.119) and preeclampsia (P<0.01, OR=1.202, 95%CI:1.123-1.286). Conclusions AUC, as well as pre-pregnancy BMI and gestational weight gain have a significant impact on outcomes of GDM, macrosomia especially, though blood glucose is controlled. Meanwhile, AUC might be considered as a predictor of macrosomia.