Objective To investigate the outcomes of increased gestational diabetes mellitus (GDM) and the influencing factors after the implementation of the new GDM diagnostic criteria. Methods A total of 1 439 GDM women who delivered in the Peking University First Hospital between May 1, 2011 and December 31, 2012 were studied and divided into two groups. Group I included the women who met the new GDM diagnostic criteria (fasting plasma glucose and 1 or 2 h plasma glucose levels for 75-g oral glucose tolerance test performed between 24 and 28 weeks of gestation were no less than 5.1, 10.0 and 8.5 mmol/L), but did not meet the National Diabetes Data Group (NDDG) criteria; and Group Ⅱ included the women who met the NDDG criteria only. Women in Group Ⅰ were further divided into two subgroups according to whether attending the one-day GDM outpatient visit. Follow-up rate and detecting rate of abnormal glucose metabolism at 6-12 weeks after delivery were analyzed. Chi-square test, t test and multivariate Logistic analysis were used for statistical analysis. Results There were 849 GDM women in GroupⅠ (59.0%, 849/1 439) and 590 (41.0%, 590/1 439) in Group Ⅱ. The follow-up rate in group Ⅰ was lower than in group Ⅱ [25.9%(220/849) vs 32.0%(189/590), χ2=6.112, P=0.013]. There were five cases of impaired fasting glucose and 34 impaired glucose tolerance in Group I; and four cases of impaired fasting glucose, 56 impaired glucose tolerance, eight impaired fasting glucose tolerance with impaired glucose tolerance and five diabetes mellitus in GroupⅡ; there were significant differences [17.7%(39/220) vs 38.6%(73/189), χ2=33.810, P=0.000]. (2) In GroupⅠ, the increased glucose level at 2 h in oral glucose tolerance test during pregnancy (OR=1.547, 95%CI: 1.038-2.306, P=0.032) and family history of diabetes mellitus (OR=1.879, 95%CI: 1.066-3.313, P=0.020) were risk factors for postpartum abnormal glucose metabolism, while breast-feeding was a protective factor (OR=0.290, 95%CI: 0.092-0.914, P=0.035). (3) In groupⅠ, the follow-up rate in those who attended the one-day GDM outpatient visit was higher than those who did not [30.7%(185/603) vs 14.2%(35/246), χ2=23.780, P=0.000], but the detecting rate of postpartum abnormal glucose metabolism were similar in women attending the one-day GDM outpatient visit and those not attending [17.8%(33/185) vs 17.1%(6/35), χ2=0.020, P=0.887]. Conclusions Increased GDM women still have glucose metabolism abnormality after delivery, especially those who have higher glucose level at 2 h after glucose intake in 75-g oral glucose tolerance test during pregnancy and who have a family history of diabetes mellitus. The one-day GDM outpatient visit may improve the follow-up rate for these women. Key words: Diabetes, gestational; Postpartum period; Follow-up studies