Sitagliptin, a DPP-4 inhibitor for the treatment of patients with type 2 diabetes: a review of recent clinical trials

Background: Dipeptidyl peptidase-4 (DPP-4) inhibitors are a new class of oral antihyperglycemic agents that enhance the body's ability to regulate blood glucose by increasing the active levels of incretins, glucagon-like peptide 1 (GLP-1) and glucose-dependent insulinotropic peptide (GIP). There are numerous DPP-4 inhibitors in development with sitagliptin as the first approved agent for the treatment of patients with type 2 diabetes. Objective: The purpose of this review is to provide an overview of the clinical trial results with sitagliptin. Methods: Clinical trials published between January 2005 (first sitagliptin publication) and November 2007 were included in this review. Medline was searched using the search terms: MK-0431 or sitagliptin. Findings: Sitagliptin, an oral, once-daily, and highly selective DPP-4 inhibitor, has been evaluated in clinical trials as monotherapy, as add-on therapy, or as initial combination therapy with metformin. Sitagliptin provided effective fasting and postprandial glycemic control in a wide range of patients with type 2 diabetes. Markers of beta-cell function (HOMA-beta and proinsulin/insulin ratio) were improved with sitagliptin treatment. In these clinical trials, sitagliptin was generally well tolerated with an overall incidence of adverse experiences comparable to placebo, a low risk of hypoglycemia or gastrointestinal adverse experiences, and a neutral effect on body weight. The findings presented in this review are limited to the specific patient population enrolled in each clinical trial and for durations for up to 1 year. Future clinical studies should evaluate whether this class of agents has the potential to delay progression and/or prevent type 2 diabetes. Conclusions: Sitagliptin has been shown to be effective and well-tolerated in various treatment regimens and may be considered for both initial therapy and as add-on therapy for patients with type 2 diabetes.