The aim of this study is to assess the long-term safety of exenatide in patients with type 2 diabetes who were treated with exenatide in Study H8O-MC-GWAA (6-month study) or Study H8O-MC-GWAD (12-month study). Study H8O-MC-GWAN serves as an open-ended extension to Studies H8O-MC-GWAA and H8O-MC-GWAD.