OBJECTIVE: To evaluate the International Association of Diabetes and Pregnancy Study Groups (IADPSG) criteria versus the American Diabetes Association (ADA) criteria for diagnosing gestational diabetes mellitus (GDM) in China. STUDY DESIGN: Overall, 3083 women with a singleton pregnancy underwent a 75-g, 2-h oral glucose tolerance test between 24 and 28 weeks of pregnancy, and both IADPSG and ADA criteria were used for GDM diagnosis. Adverse pregnancy outcomes (APOs), including preterm birth, required Cesarean section, preeclampsia, macrosomia and low birth weight, were recorded and analyzed. RESULT: IADPSG and ADA criteria diagnosed 19.9% and 7.98% of women with GDM, respectively (P<0.001). IADPSG criteria has a stronger capacity of predicting APOs than ADA criteria (odds ratio (OR) = 1.84, 95% confidence interval (CI): 1.52-2.25 for IADPSG, and OR = 1.54, 95% CI: 1.16-2.05 for ADA). CONCLUSION: IADPSG criteria increase GDM diagnosis by almost twofold. GDM diagnosed by IADPSG criteria is more associated with APOs, although the economic impact needs further evaluation.