This trial is conducted globally (the United States of America excepted). This trial is designed to show the effect of treatment with liraglutide when added to existing glimepiride therapy and to compare this to both glimepiride monotherapy and to rosiglitazone as add-on therapy to glimepiride.

Inclusion Criteria:

• Type 2 diabetes
• Treatment with oral anti-diabetic drugs for at least 3 months
• HbA1c: 7.0-11.0 % (both incl.) in subjects on OAD monotherapy. 7.0-10.0 % (both incl.) in subjects on OAD combination therapy
• Body Mass Index (BMI) less than or equal to 45.0 kg/m2.

Exclusion Criteria:

• Treatment with insulin within the last three months
• Treatment with any drug that could interfere with the glucose level
• Any serious medical condition
• Females who are pregnant, have the intention of becoming pregnant or are breastfeeding