Dose-finding of Semaglutide Administered Subcutaneously Once Daily Versus Placebo and Liraglutide in Subjects With Type 2 Diabetes

Inclusion Criteria: * Male or female, age at least 18 years at the time of signing informed consent. * Subjects should be on stable diabetes treatment consisting of diet and exercise with or without metformin (at least 1500 mg daily or maximum tolerated dose documented in the patient medical record) for at least 90 days prior to screening * HbA1c (glycosylated haemoglobin): 53-86 mmol/mol (7.0-10.0%) (both inclusive) * BMI: 25.0 - 40.0 kg/m\^2 (both inclusive) Exclusion Criteria: * Simultaneous participation in any other clinical trial of an investigational medicinal product * Female who is pregnant, breast-feeding or intends to become pregnant or is of child-bearing potential and not using adequate contraceptive methods throughout the trial including the 7 weeks follow-up period (adequate contraceptive measures as required by local regulation or practice). Germany: Only highly effective methods of birth control are accepted (i.e. one that results in less than 1% per year failure rate when used consistently and correctly such as implants, injectables, combined oral contraceptives, some intrauterine device), or sexual abstinence or vasectomised partner. United Kingdom: Adequate contraceptive measures are defined as established use of oral, injected or implanted hormonal methods of contraception, placement of an intrauterine device or intrauterine system, barrier methods of contraception (condom or occlusive cap with spermicidal foam/gel/film/cream/suppository), female sterilisation, male sterilisation (where partner is sole partner of subject), or true abstinence (when in line with preferred and usual lifestyle) * Treatment with any medication for the indication of diabetes or obesity other than stated in the inclusion criteria in a period of 90 days before screening (an exception is short-term insulin treatment for acute illnesses for a total of below or equal to 14 days) * Anticipated initiation or change in concomitant medications (for more than 14 consecutive days or on an frequent basis) known to affect weight or glucose metabolism (e.g. orlistat, thyroid hormones, corticosteroids) * History of pancreatitis (acute or chronic) * Screening calcitonin above or equal to 50 ng/L * Family or personal history of Multiple Endocrine Neoplasia Type 2 (MEN2) or Medullary Thyroid Carcinoma (MTC) * Severe to moderate renal impairment defined as GFR, estimated below 60 ml/min/1.73 m\^2 as per CKD-EPI (Chronic Kidney Disease Epidemiology) * Within the past 180 days before screening any of the following: Myocardial infarction, stroke or hospitalisation for unstable angina and/or transient ischemic attack * Currently planned coronary, carotid or peripheral artery revascularisation * Patients presently classified as being in New York Heart Association (NYHA) Class III or IV