Safety and Efficacy Study for the Treatment of Painful Diabetic Neuropathy

Inclusion Criteria: * Age ≥ 18 years to ≤ 75 years * Documented history of Type I or II diabetes with current treatment control (glycosylated hemoglobin A1c of ≤ 10.0% at Screening) and currently on oral medication and/or insulin * Diagnosis of painful diabetic peripheral neuropathy in both lower extremities * Lower extremity pain for at least 6 months * Visual analog scale (VAS) score of ≥ 40 mm at Initial Screening (0 mm = no pain - 100 mm very severe pain) * Symptoms from the Brief Pain Neuropathy Screening (BPNS) is ≤ 5 point difference between legs at Initial Screening * The average daily pain intensity score of the Daily Pain and Sleep Interference Diary completed after medication wash-out is ≥ 4 with a standard deviation ≤ 2 * The physical examination component of the Michigan Neuropathy Screening Instrument Score (MNSI) is ≥ 3 at Screening * Stable treatment of diabetes for at least 3 months with no anticipated changes in medication regimen, and no new symptoms associated with diabetes * If female of childbearing potential, negative urine pregnancy test at screening and using acceptable method of birth control during the study Exclusion Criteria: * Peripheral neuropathy caused by condition other than diabetes * Other pain more severe than neuropathic pain * Progressive or degenerative neurological disorder * Myopathy * Inflammatory disorder of the blood vessels (inflammatory angiopathy, such as Buerger's disease) * Active infection * Chronic inflammatory disease (e…