Background The prevalence of type 2 diabetes mellitus (T2DM) and obesity is increasing in Korea. Clinical studies in patients with T2DM have shown that combining the glucagon-like peptide-1 receptor agonist exenatide twice daily with basal insulin is an effective glucose-lowering strategy. However, these studies were predominantly conducted in non-Asian populations. Methods We conducted a subgroup analysis of data from a multinational, 30-week, randomized, open-label trial to compare the effects of exenatide twice daily (n=10) or three times daily mealtime insulin lispro (n=13) among Korean patients with T2DM inadequately controlled (glycosylated hemoglobin [HbA1c] >7.0%) on metformin plus optimized insulin glargine. Results Exenatide twice daily and insulin lispro both reduced HbA1c (mean −1.5% and −1.0%, respectively; P<0.01 vs. baseline). Fasting glucose and weight numerically decreased with exenatide twice daily (−0.7 mmol/L and −0.7 kg, respectively) and numerically increased with insulin lispro (0.9 mmol/L and 1.0 kg, respectively). Minor hypoglycemia occurred in four patients receiving exenatide twice daily and three patients receiving insulin lispro. Gastrointestinal adverse events were the most common with exenatide twice daily treatment. Conclusion This analysis found treatment with exenatide twice daily improved glycemic control without weight gain in Korean patients with T2DM unable to achieve glycemic control on metformin plus basal insulin.