A Study Comparing the Efficacy and Safety of ABT-652 to Placebo in Subjects With Diabetic Neuropathic Pain

Inclusion Criteria: * Subject is between the ages of 18-75 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 a mean average score of greater than 4 on the 24 hour average pain score (0-10 numerical rating scale) prior to the Baseline Visit. * Subject has been on a medication for diabetic neuropathic pain for the past 3 months. Exclusion Criteria: * Subject has clinically symptomatic neuropathic pain conditions that cannot 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. * Subject has taken an opioid chronically, excluding tramadol within the last 3 months prior to Screening.