An Open-label follow-on Trial to Assess the Long-term Safety and Efficacy of Oral SPM 927 in Subjects With Diabetic Neuropathy

Inclusion Criteria: * Subject has successfully completed a previous trial with SPM 927 in diabetic neuropathy and, in the investigator's opinion, would benefit from long-term administration of SPM 927. * Subject has stable, good or fair diabetic control (HbA1c ≤10% ). Exclusion Criteria: * Subject has other conditions that cause neuropathic pain at least as severe as the diabetic pain, i.e. peripheral arterio-vascular disease. * Subject receives treatment for seizures. * Subject has had an amputation related to diabetes, other than toe amputation. * Subject has major skin ulcers. * Subject has clinically significant ECG abnormalities. * Subject expects to take during the study: TCAs, mexiletine hydrochloride, lidoderm patch, tramadol, AEDs, dextromethorphan, opioids, capsaicin, skeletal muscle relaxants, benzodiazepines or over-the-counter medications with centrally acting properties. * Subject has laboratory values which are outside the normal range and judged by the investigator to be clinically significant. * Subject has liver function tests (AST, ALT, alkaline phosphatase, total bilirubin, or GGT) ≥ 2x ULN at Visit 1. * At Visit 1, subject has impaired renal function, i.e., creatinine clearance (ClCr) is lower than 60 mL/min.