BACKGROUND AND OBJECTIVE: In two previously reported multi-center, randomized, open-label, comparator (insulin) controlled trials in patients with type 2 diabetes sub-optimally controlled with metformin and a sulfonylurea, treatment with exenatide and insulin analogue therapy produced similar reductions in glycosylated hemoglobin A(1c) (A1C). However, treatment with exenatide was associated with a reduction in body weight while insulin analogue therapy was associated with weight gain. This analysis further characterizes the relative impact of commonly employed insulin analogues versus exenatide on weight change over a 6-month period. RESEARCH DESIGN AND METHODS: In this pooled post-hoc analysis of two trials, 1047 subjects with diabetes were compared regarding the relative impact of an adjunctive treatment - an insulin analogue (glargine or biphasic insulin aspart) or exenatide (5 mug twice daily for 4 weeks, 10 mug thereafter) - on body weight. RESULTS: While exenatide treatment provided similarly effective glycemic control compared with insulin analogue therapy, it was also associated with weight reduction in the majority of subjects (73.3%, averaging 3 kg decrease by endpoint), with approximately 22% achieving > or =5% weight loss, and 3.2% of subjects achieving > or =10% weight loss. In contrast, by the end of the study most insulin-treated subjects (75.9%) had gained weight (mean 3 kg). Only 2% of insulin-treated subjects achieved > or =5% weight loss, and 0.2% of subjects achieved > or =10% weight loss. CONCLUSIONS: These findings support the use of exenatide as a treatment option in insulin-naive subjects with type 2 diabetes and who are overweight and sub-optimally controlled by metformin and sulfonylurea. However, these results should be interpreted with caution given the exploratory nature of this post-hoc analysis.