Effect of Liraglutide as add-on to Metformin Compared to Either Liraglutide or Metformin Alone, or to a Combination of Metformin and a SU (Sulphonylurea) Agent in Subjects With Type 2 Diabetes

Inclusion Criteria: * Patients diagnosed with type 2 diabetes and treated with at least 50 % of maximum dose(s) of OHA(s) for at least three months * Duration of type 2 diabetes diagnosis at least one year * HbA1c 8.0-13.0%, both inclusive * Body Mass Index (BMI) between 25-40 kg/m\^2, both inclusive. Exclusion Criteria: * Current treatment with thiazolidinediones or insulin initiated within the last four months prior to trial * Impaired liver function * Impaired renal function * Cardiac problems * Uncontrolled treated/untreated hypertension * Cancer or any clinically significant disease or disorder, except for conditions associated to the type 2 diabetes, which in the Investigator's opinion could interfere with the results of the trial * Recurrent major hypoglycaemia as judged by the Investigator * Known or suspected allergy to trial product or related products * Use of any drug (except for OHAs), which in the Investigator's opinion could interfere with the glucose level * Known or suspected abuse of alcohol or narcotics * Any contraindications to metformin or glimepiride according to the local guidelines