A Randomized, Double-blind, Placebo- and Active-controlled Study of the Electric Current Effects of ABT-639 on the Spontaneous Activity of Pain Sensory Receptors in Patients With Diabetic Peripheral Neuropathy

Inclusion Criteria * Subject is between the ages of 18 to 75 years with a diagnosis of diabetes mellitus and must have a diagnosis of painful distal symmetric diabetic polyneuropathy and presence of ongoing pain due to diabetic peripheral neuropathy for at least 6 months. * Subject must have an average score of greater than or equal to 4 on the 24 hour average pain score (0-10 numerical rating scale) collected over approximately 7 days prior to the Baseline Visit. Exclusion Criteria * Subject has clinically symptomatic neuropathic pain conditions that can not be distinguished from diabetic neuropathic pain or interfere with the pain assessments of diabetic neuropathic pain. * A subject has newly diagnosed or clinically significant medical conditions or mental disorders that would preclude participation or would interfere with diabetic neuropathic pain assessments or other functions. * Subject has clinically significant abnormalities in clinical laboratory tests.