A Trial Comparing Insulin Degludec/Liraglutide and Insulin Degludec in Combination With Metformin in Chinese Subjects With Type 2 Diabetes Mellitus Inadequately Controlled With Basal Insulin Therapy and Metformin With or Without One Other Oral Antidiabetic Drug (OAD)

This trial is conducted in Asia. The aim of this trial is to confirm the superiority of insulin degludec/liraglutide versus insulin degludec in controlling glycaemia in Chinese subjects with type 2 diabetes mellitus after 26 weeks of treatment

Inclusion Criteria: Informed consent obtained before any trial-related activities. Trial-related activities are any procedures that are carried out as part of the trial, including procedures to determine suitability for the trial - Male or female, age at least 18 years at the time of signing inform consent - Type 2 diabetes mellitus (clinically diagnosed) - HbA1c (glycosylated haemoglobin) above or equal to 7.5% by central laboratory analysis, with the aim of a median of 8.5%. When approximately 50% of the randomised subjects have an HbA1c above 8.5%, the remaining subjects randomised must have an HbA1c below or equal to 8.5% or when approximately 50% of the subjects randomised have an HbA1c below or equal to 8.5%, the remaining subjects randomised must have an HbA1c above 8.5% - Current treatment for at least 90 calendar days prior to screening with basal insulin plus metformin plus/minus α-glucosidase inhibitors, sulphonylureas, glinides or thiazolidinediones. Subjects should be on a stable dose for at least 60 calendar days prior to screening of: Basal insulin 20-50 units (U)/day (both inclusive) ( Individual fluctuations of plus/minus 5U during the 60 day period prior to the day of screening are acceptable.) on the day of screening in combination with: - Metformin (above or equal to 1500 mg or max tolerated dose) or - Metformin (above or equal to 1500 mg or max tolerated dose) and sulphonylureas (above or equal to half of the max approved dose according to local label) or - Metformin (above or equal to 1500 mg or max tolerated dose) and glinide (at least half of the max approved dose according to local label) or - Metformin (above or equal to 1500 mg or max tolerated dose) and α-glucosidase inhibitors (AGI) (at least half of the max approved dose according to local label) or - Metformin (above or equal to 1500 mg or max tolerated dose) and thiazolidinediones (at least half of the max approved dose according to local label) - Body mass index (BMI) above or equal to 24 kg/m^2 Exclusion Criteria: Current use of any antidiabetic drug (except for basal insulin, metformin, α-glucosidase inhibitors, sulphonylureas, glinides or thiazolidinediones) or anticipated change in concomitant medication, that in the investigator´s opinion could interfere with glucose level (e.g. systemic corticosteroids) - Treatment with glucagon like peptide -1 receptor agonists, or dipeptidyl-peptidase-4 inhibitors or insulin (except for basal insulin) within 90 days prior to Visit 1 - Impaired liver function defined as alanine aminotransferase above or equal to 2.5 times upper normal range - Impaired renal function defined as serum-creatinine above or equal to 133 μmol/L for males and above or equal to 125 μmol/L for females, or as defined according to local contraindications for metformin Screening calcitonin above or equal to 50 ng/L - Personal or family history of medullary thyroid carcinoma (MTC) or multiple endocrine neoplasia type 2 (MEN2) - Cardiac disorder defined as: congestive heart failure (NYHA class III-IV), diagnosis of unstable angina pectoris, cerebral stroke and/or myocardial infarction within the last 12 months prior to screening and/or planned coronary, carotid or peripheral artery revascularisation procedures - Severe uncontrolled treated or untreated hypertension (systolic blood pressure above or equal to 180 mm Hg or diastolic blood pressure above or equal to 100 mm Hg) - Proliferative retinopathy or maculopathy (macular oedema) requiring acute treatment - History of pancreatitis (acute or chronic)