Arena Pharmaceuticals was developing APD-597 (JNJ-38431055), a small molecule, an orally active agonist of the G-protein coupled receptor 119 (GPR119), for the treatment of Type 2 diabetes mellitus. JNJ-38431055 was selected for preclinical development based on a good balance between agonist potency, intrinsic activity and in particular on its good solubility and reduced drug-drug interaction potential. In addition, extensive in vivo studies showed a more favorable metabolic profile that may avoid the generation of long-lasting metabolites with the potential to accumulate in clinical studies. In humans, single-dose oral JNJ-38431055 increased postmeal plasma glucagon-like peptide 1 (GLP-1), glucose-dependent insulinotropic peptide (GIP), and peptide YY (PYY) concentrations but did not significantly decrease glucose excursion or increase insulin secretion. However, in a graded glucose infusion study, JNJ-38431055 was shown to induce a higher insulin secretion rate (ISR) relative to placebo at elevated plasma glucose levels. These studies provide evidence for the potential efficacy of JNJ-38431055 as an antidiabetes agent in humans.