This trial is conducted in the United States of America (USA). The study will compare A1C reduction achieved in patients receiving biphasic insulin aspart 70/30 once or twice daily to patients receiving exenatide twice daily. Patients enrolled in the study will be insulin naive patients who have not achieved glycemic control with metformin and sulfonylurea.

Inclusion Criteria:

• Type 2 diabetes
• HbA1C: At least 8%
• Patients that were never treated with insulin before
• Current therapy with metformin and a sulfonylurea.

Exclusion Criteria:

• History of recurrent, severe hypoglycemia
• Hepatic insufficiency: ALT, AST or alkaline phosphatase > 2.5 times upper limits of laboratory's normal
• Renal insufficiency: serum creatinine > 1.3 mg/dL (males) or > 1.2 mg/dL (females)
• Severe gastrointestinal disease, including gastroparesis