Efficacy and Safety of Oral Semaglutide Using a Flexible Dose Adjustment Based on Clinical Evaluation Versus Sitagliptin in Subjects With Type 2 Diabetes Mellitus.

Inclusion Criteria: Main phase (the inclusion criteria for the main phase are not reassessed for the extensionphase):

• Informed consent obtained before any trial-related activities. Trial-relatedactivities are any procedures that are carried out as part of the trial, includingactivities to determine suitability for the trial
• Male or female, age above or equal to 18 years at the time of signing informedconsent. For Korea only: Male or female, age above or equal to 19 years at the time ofsigning informed consent
• Diagnosed with type 2 diabetes mellitus for at least 90 days prior to day of screening
• HbA1c (glycosylated haemoglobin) 7.5-9.5% (58-80 mmol/mol) (both inclusive)
• Treatment target of HbA1c below 7.0% (53 mmol/mol), as judged by the investigator
• Stable daily dose(s) of 1-2 of the following anti-diabetic drugs within 90 days priorto the day of screening:
• Metformin (equal or above 1500 mg or maximum tolerated dose as documented in thesubject medical record)
• Sulfonylureas (equal or above half of the maximum approved dose according to locallabel or maximum tolerated dose as documented in subject medical record)
• Sodium glucose co-transporter 2 inhibitors
• Thiazolidinediones (equal or above half of the maximum approved dose according tolocal label or maximum tolerated dose as documented in subject medical record) Extension phase:
• Informed consent for the extension phase obtained before any trial-related activitiesfor the extension phase.
• On randomised treatment with or without rescue medication at week 52.

Exclusion Criteria: Main phase (the exclusion criteria for the main phase are not reassessed for the extensionphase):

• Female who is pregnant, breast-feeding or intends to become pregnant or is ofchild-bearing potential and not using an adequate contraceptive method (adequatecontraceptive measure as required by local regulation or practice). For certainspecific countries: Additional specific requirements apply
• Any disorder, which in the investigator's opinion might jeopardise subject's safety orcompliance with the protocol
• Family or personal history of Multiple Endocrine Neoplasia Type 2 or Medullary ThyroidCarcinoma
• History of pancreatitis (acute or chronic)
• History of major surgical procedures involving the stomach potentially affectingabsorption of trial product (e.g. subtotal and total gastrectomy, sleeve gastrectomy,gastric bypass surgery)
• Any of the following: myocardial infarction, stroke or hospitalisation for unstableangina or transient ischaemic attack within the past 180 days prior to the day ofscreening and randomisation
• Subjects presently classified as being in New York Heart Association Class IV
• Planned coronary, carotid or peripheral artery revascularisation known on the day ofscreening
• Subjects with alanine aminotransferase above 2.5 x upper normal limit
• Renal impairment defined as Estimated Glomerular Filtration rate 60 mL/min/1.73 m^2 asper Chronic Kidney Disease Epidemiology Collaboration formula
• Treatment with any medication for the indication of diabetes or obesity other thanstated in the inclusion criteria in a period of 90 days before the day of screening.An exception is short-term insulin treatment for acute illness for a total of below orequal to 14 days
• Proliferative retinopathy or maculopathy requiring acute treatment. Verified by fundusphotography or dilated fundoscopy performed within 90 days prior to randomisation
• History or presence of malignant neoplasms within the last 5 years (except basal andsquamous cell skin cancer and carcinoma in situ)
• History of diabetic ketoacidosis Extension phase: There are no new exclusion criteria for the extension phase