Good glycemic control among patients with type 2 diabetes reduces the risk of diabetes-related microvascular complications.Many antihyperglycemic agents are licensed for the treatment of type 2 diabetes, but questions regarding the long-term cardiovascular safety of some of these agents have been raised. International regulatory agencies have responded by requiring that new antihyperglycemic agents not only show glucose-lowering ability but also are not associated with clinically meaningful increases in rates of major adverse cardiovascular events.

Sitagliptin, an orally administered dipeptidyl peptidase 4 (DPP-4) inhibitor, prolongs the action of incretin hormones, including glucagon-like peptide 1 and glucose-dependent insulin tropic polypeptide, by inhibiting their breakdown. This improves glycemic control in patients with type 2 diabetes, primarily by suppressing glucagon levels and increasing endogenous insulin secretion. Two previous cardiovascular outcome trials of other DPP-4 inhibitors did not show an increase or decrease in the number of major adverse cardiovascular events but did raise safety concerns regarding a possible elevated risk of hospitalization for heart failure, with meta-analyses of randomized, controlled trials suggesting an increase of 24 to 25% in such a risk associated with these agents.

In the Trial Evaluating Cardiovascular Outcomes with Sitagliptin (TECOS), we assessed the long-term cardiovascular safety of adding sitagliptin to usual care, as compared with usual care alone, in patients with type 2 diabetes and established cardiovascular disease.

To know the effect of Sitagliptin please find the attached article

http://www.nejm.org/doi/full/10.1056/NEJMoa1501352#t=article