Safety and Efficacy of Exenatide in Patients With Type 2 Diabetes Using a Thiazolidinedione or a Thiazolidinedione and Metformin

Inclusion Criteria: * Diagnosed with type 2 diabetes * If treated with a thiazolidinedione (TZD) alone, the TZD dose must have been stable for at least 120 days * The dose of TZD must be: Rosiglitazone (≥4 mg/day) or pioglitazone (≥30 mg/day) * The metformin dose has been stable for at least 90 days * Have suboptimal glycemic control as evidenced by an HbA1c between 7.1% and 10.0%, inclusive. * Have a body mass index (BMI): 25 kg/m2 \< BMI \< 45 kg/m2. Exclusion Criteria: * Have participated in this study previously or any other study using exenatide (AC2993/LY2148568) or glucagon-like peptide-1 (GLP-1) analogs, or have been previously treated with exenatide or GLP-1 analogs * 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 of screening. This criterion includes drugs that have not received regulatory approval for any indication at the time of study entry. * Have been treated with exogenous insulin for more than 1 week within the 2 months prior to screening * Used drugs for weight loss (e.g., orlistat, rimonabant, sibutramine, or similar over-the-counter medications) within 3 months prior to screening. * Are currently treated with any of the following excluded medications: * Sulfonylurea or meglitinide derivatives (e.g., repaglinide or nateglinide) within 3 months prior to screening * Alpha-glucosidase inhibitor (e.g., miglitol or acarbose) within 3 months of screening * Dipeptidyl peptidase-4 (DPP-4) inhibitors (e.g., sitagliptin or vildagliptin) within 3 months prior to screening * Pramlintide acetate injection within 3 months prior to screening * Drugs that directly affect gastrointestinal motility, including, but not limited to: Metoclopramide, cisapride, and chronic macrolide antibiotics * Are receiving chronic (lasting longer than 2 weeks) systemic glucocorticoid therapy (excluding topical and inhaled preparations) or have received such therapy within the 4 weeks immediately preceding study start