The primary purpose is to investigate the safety and efficacy of SPM927 in patients with Painful Diabetic Neuropathy

Inclusion Criteria:

• Subject has clinically diagnosed pain attributed to diabetic distal sensory motor polyneuropathy for 1-5 years and a diagnosis of diabetes mellitus (Type I or Type II).
• Subjects must have at least moderate pain (mean pain intensity ≥ 4 out of 10 during the baseline week on Likert scale).
• subjects must have good or fair diabetic control (Hgb A1c < 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 any amputations other than diabetically-related toe amputations.
• Subject has major skin ulcers.
• Subject has clinically significant ECG abnormalities.
• Subject is expected to take within 7 days prior to randomization and during the study: TCAs, mexiletine hydrochloride, lidoderm patch, tramadol, AEDs, dextromethorphan, opioids, capsaicin, nonsteroidal anti-inflammatory drugs, acetaminophen / paracetamol, skeletal muscle relaxants, benzodiazepines, alpha-2-agonists (e.g. clonidine), drugs indicated for sleep disturbance (e. g. zolpidem tartrate, zaleplon) and 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.
• At study entry, subject has liver function tests values (AST, ALT,alkaline phosphatase, total bilirubin and GGT) 2 times upper limit of normal.
• subject has impaired renal function, i.e., creatinine clearance is lower than 60 mL/min.