The Efficacy and Safety of Liraglutide Compared to Sitagliptin, Both in Combination With Metformin in Chinese Subjects With Type 2 Diabetes

Inclusion Criteria: * Male or female, age at least 18 years and below 80 years at the time of signing informed consent * Subjects diagnosed type 2 diabetes mellitus and treated with metformin monotherapy at a stable dose of at least 1500 mg daily or maximum tolerated dose above or equal to 1000 mg daily for at least 60 days prior to screening * HbA1c 7.0-10.0% (both inclusive) * Body mass index below or equal to 45.0 kg/m\^2 Exclusion Criteria: * Treatment with glucose lowering agent(s) other than stated in the inclusion criteria in a period of 60 days prior to screening. An exception is short-term treatment (below or equal to 7 days in total) with insulin in connection with intercurrent illness * History of chronic pancreatitis or idiopathic acute pancreatitis * Any chronic disorder or severe disease which at the discretion of the investigator might jeopardise subject's safety or compliance with the protocol * Screening calcitonin value above or equal to 50 ng/l * Personal or family history of medullary thyroid carcinoma or multiple endocrine neoplasia syndrome type 2 * Diagnosis of malignant neoplasm in the previous 5 years (except basal cell skin cancer or squamous cell skin cancer) * Any contraindications to liraglutide, sitagliptin or metformin according to local labelling