OBJECTIVE： To investigate health effect， cost and cost-effect of sitagliptin in the treatment of type 2 diabetes mellitus. METHODS： By retrieving PubMed， Web of Science， different diabetes mellitus therapy plans were selected and compared， including  sitagliptin combined with metformin vs. glimepiride combined with metformin， sitagliptin combined with metformin vs. acarbose combined with metformin， sitagliptin 100 mg vs. acarbose 100 mg，tid. UKPDS Outcomes Model was used to compare the long-term medical costs and outcomes among different therapy plans， and evaluated their economic effects. The model operated for 40 years， and both future costs and clinical benefits were discounted by 3.0％. RESULTS： Compared to the therapy of glimepiride or acarbose combined with metformin， the therapy of sitagliptin combined with metformin prolonged 0.03 and 1.22 years of life （LYG） per patient， and the additional costs were 44 055 yuan and 1 923 yuan for each year of life obtained， respectively， which were lower than 3-fold GDP （125 724 yuan） suggested by WHO； the add-on of sitagliptin provided a gain of 0.02 quality adjusted life year （QALY） and 0.95 QALY per patient， and the additional costs were 58 717 yuan and 2 475 yuan for each QALY respectively， which were lower than 3-fold GDP （125 724 yuan） suggested by WHO. Compared to acarbose monotherapy （100 mg， tid）， the sitagliptin monotherapy （100 mg/d） was dominant， with longer LYGs （0.72 years） and QALYs （0.58 years） gained and lower cost （557 yuan saved）. CONCLUSIONS： According to 3-fold GDP （125 724 yuan） recommended by WHO as threshold， sitagliptin demonstrate good cost-effectiveness in the treatment of type 2 diabetes mellitus.