2-Pyrrolidinecarbonitrile, 4-fluoro-1-[2-[(2-hydroxy-1,1-dimethylethyl)amino]acetyl]-, (2S,4S)-, benzenesulfonate (1:1)

TS-021 is a dipeptidyl peptidase 4 (DPP-4) inhibitor potentially for the treatment of type 2 diabetes. TS-021 and/or metformin significantly improved glucose tolerance and glucagon-like peptide-1 (GLP-1) level, and TS-021 alone or in combination with metformin significantly increased the plasma insulin level after nutrient ingestion. In the chronic treatment study, TS-021 in combination with metformin significantly lowered the glycosylated hemoglobin level, plasma insulin level, and α-cell-to-β-cell area ratio in pancreatic islets. TS-021 exhibited a significant improvement in glucose tolerance by increasing the plasma insulin level during oral glucose tolerance tests.