• To test the hypothesis that glycemic control achieved with exenatide administered subcutaneously before lunch and dinner is noninferior to that obtained with the administration before breakfast and dinner in patients with type 2 diabetes. [ Time Frame: 12 weeks ] [ Designated as safety issue: No ]
  

• To compare exenatide administered either before breakfast and dinner or before lunch and dinner with respect to various pharmacodynamic measurements, body weight, and safety and tolerability. [ Time Frame: 12 weeks ] [ Designated as safety issue: No ]
  

Inclusion Criteria:

• Diagnosed with type 2 diabetes.
• Have been treated with one of the following treatment regimens for at least three months prior to screening: *metformin alone; *sulfonylurea (SU) alone; *thiazolidinedione (TZD) alone; *a combination of metformin and SU; *a combination of metformin and TZD.
• HbA1c between 7.1% and 10.0%, inclusive.
• Body Mass Index (BMI) > 25 kg/m^2 and < 45 kg/m^2

Exclusion Criteria:

• Have participated in an interventional, medical, surgical, or pharmaceutical study (a study in which an experimental drug, medical, or surgical treatment was given) within 30 days prior to screening.
• Have characteristics contraindicating metformin, SU, or TZD use.
• Are receiving chronic (lasting longer than 2 weeks) systemic glucocorticoid therapy (excluding topical and inhaled preparations) or have received such therapy within 2 weeks immediately prior to screening.
• Have used any prescription drug to promote weight loss within 3 months prior to screening.
• Are currently treated (for greater than 2 consecutive weeks) with any of the following excluded medications: *insulin within 3 months prior to screening; *alpha-glucosidase inhibitors within 3 months prior to screening; *meglitinides within 3 months prior to screening; *drugs that directly affect gastrointestinal motility