Comparison of Two NN5401 Formulations Versus Insulin Glargine, All in Combination With Metformin in Subjects With Type 2 Diabetes

Inclusion Criteria: * Informed consent obtained before any trial-related activities. (Trial-related activities are any procedure that would not have been performed during normal management of the subject.) * Insulin naïve type 2 diabetes subjects (as diagnosed clinically) for at least 3 months (no previous insulin treatment or previous short term insulin treatment maximum 14 days within the last 3 months) * Treatment with one or two oral anti-diabetic drugs (OADs): metformin, sulfonylurea, other insulin secretagogue (e.g. repaglinide, nateglinide), alpha-glucosidase inhibitors for at least 2 month at a stable maximum tolerated dose or at least half maximum allowed dose according to locally approved summary of product characteristics (SPC) * HbA1c, 7.0 - 11.0 % (both inclusive) * Body Mass Index (BMI), 25.0 - 37.0 kg/m\^2 (both inclusive) Exclusion Criteria: * Metformin contraindication according to local practice * Thiazolidinedione (TZD) treatments within the previous three months prior to Visit 1 * Any systemic treatment with products, which in the investigator's opinion could interfere with glucose or lipid metabolism (e.g. systemic corticosteroids) within 3 months prior to randomisation * Subject has a clinically significant, active (during the past 12 months) disease of the gastrointestinal, pulmonary, neurological, genitourinary, or haematological system that, in the opinion of the investigator, may confound the results of the trial or pose additional risk in administering trial product