Abstract: Certain constrained cyano compounds are useful as inhibitors of post-proline/alanine cleaving amino-dipeptidases. Accordingly, these compounds can be employed, alone or with another therapeutic agent, to treat diabetes (especially, Type II diabetes), hyperglycemia, Syndrome X, diabetic complications, hyperinsulinemia, obesity, atherosclerosis and related diseases, as well as various immunomodulatory diseases and chronic inflammatory bowel disease.