The present invention is directed to pyrrolidinylaminoacetyl pyrrolidine boronic acid compounds that display selective, potent dipeptidyl peptidase IV inhibitory activity. These compounds are useful for the treatment of disorders that can be regulated or normalized via inhibition of DPP-IV including those characterized by impaired glycemic control such as Diabetes Mellitus and related conditions. The compounds can be administered alone or with another medicament that displays pharmacological activity for treatment of these and other diseases.