A Clinical Trial Comparing Efficacy and Safety of Insulin Degludec/Liraglutide (IDegLira) in Subjects With Type 2 Diabetes Mellitus Using Two Different Titration Algorithms

Inclusion Criteria: * Type 2 diabetes mellitus * Male or female equal to or above 18 years of age * HbA1c (glycosylated haemoglobin) 7.0 - 10.0% \[53 mmol/mol - 86 mmol/mol\] (both inclusive), confirmed by the central laboratory * Stable daily treatment with metformin (above or equal to 1500 mg or max tolerated dose) with or without pioglitazone (above orequal to 30 mg) for at least 90 days prior to screening * Body Mass Index (BMI) below or equal to 40 kg/m\^2 Exclusion Criteria: * Current use of any anti-diabetic drugs (except for metformin and pioglitazone) or anticipated change in concomitant medication, which, in the opinion of the investigator, could interfere with the glucose metabolism (e.g. systemic corticosteroids) * Previous and / or current treatment with insulin (short term treatment due to intercurrent illness, including gestational diabetes, is allowed at the discretion of the investigator) * Treatment with glucagon-like peptide-1 (GLP-1) receptor agonists, sulpfonylurea, glinides, dipeptidyl peptidase 4 (DPP-4) inhibitors or sodium-glucose co-transporter 2 (SGLT2) inhibitors within 90 days prior to the screening visit * Impaired liver function, defined as alanine aminotransferase (ALAT) above or equal to 2.5 times upper normal range (UNR) * Impaired renal function defined as serum-creatinine above or equal to 133 micromol/L (above or equal to 1.5 mg/dL) for males and above or equal to 125 micromol/L (above or equal to 1.4 mg/dL) for females, or as defined according to local contraindications for metformin * Screening calcitonin above or equal to 50 ng/L * Proliferative retinopathy or maculopathy (macular oedema) requiring acute treatment, according to investigator's clinical judgment * Personal or family history of medullary thyroid carcinoma (MTC) or multiple endocrine neoplasia type 2 (MEN2) * History of pancreatitis (acute or chronic)