DPP4 and diabetes mellitus: This article is a brief review of the current non-insulin agents for diabetes mellitus in the United States, namely, sulfonylureas, biguanides, thiazolidinediones, meglitinides, α-glucosidase inhibitors, glucacon-like peptide-1 receptor agonists, dipeptidyl-peptidase-4 inhibitors, amylin agonists, bromocriptine, and colesevelam.