First novel once-weekly DPP-4 inhibitor, trelagliptin, for the treatment of type 2 diabetes mellitus.

INTRODUCTION: Dipeptidyl peptidase-4 (DPP-4) inhibitors are weight neutral and well tolerated, and provide better glycaemic control for a longer period compared to conventional therapies. Despite the fact that various drugs are available, glycaemic control remains suboptimal in approximately half of patients with type 2 diabetes mellitus; one of the major reasons for low medication adherence. AREAS COVERED: A novel DPP-4 inhibitor, trelagliptin, was approved in Japan in March 2015, and is the first once-weekly oral antidiabetic agent in the world. In this review, current issues concerning medication adherence for the treatment of diabetes are discussed followed by a summary of the characteristics and future expectations of trelagliptin, by reviewing the recent phase I, II, and III clinical studies of trelagliptin. EXPERT OPINION: Trelagliptin has demonstrated superiority to placebo and non-inferiority to alogliptin, indicating its efficacy and tolerance in Japanese patients. Trelagliptin is expected to improve adherence and prevent complications. Due to the convenient dosing regimen, it is expected to be widely used in the clinical setting. A large-scale long-term study will help further confirm its long-term efficacy and safety, patients' satisfaction, and medication adherence.