The primary objective of the trial is to assess the tolerability and safety of long-term SPM 927 administration 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.