Safety and Efficacy Study of ADL5859 in Participants With Neuropathic Pain Associated With Diabetic Peripheral Neuropathy

Inclusion Criteria: * Male and female participants between 18 and 75 years of age, inclusive * Body weight of at least 45 kilograms (kg) * Diabetes mellitus (type I or II) that is documented to be under stable glycemic control over a period of at least 3 months, as indicated by a glycosylated hemoglobin (HbgAIC) of less than or equal to 12% and a stable dose of insulin or oral diabetic medication for 90 days prior to starting study medication * No change in diabetic medications is planned for the duration of the study * Evidence of symmetrical, bilateral pain in the lower extremities due to diabetic peripheral neuropathy (DPN) * Presence of daily pain due to DPN for at least 3 months * Score greater than or equal to 3 on the physical examination portion of the Michigan Neuropathy Screening Instrument (MNSI) * Average weekly pain score of greater than or equal to 4 on the numeric pain rating scale (NPRS) for symmetrical neuropathic pain in the feet and legs * For male participants, be surgically sterile or agree to use an appropriate method of contraception * For female participants of childbearing potential, be surgically sterile or using an intrauterine device, or injectable, transdermal, or combination oral contraceptive deemed highly effective by the Food and Drug Administration (FDA) * Be willing and able to comply with the protocol requirements * Be able to understand and willing to provide written informed consent in English Exclusion Criteria: * Presence of pain con…