Diabetes mellitus is the most common cause of neuropathy in the Western World, with up to 50% of patients developing neuropathy as a long-term complication of the illness, of whom 10% experience pain. Diabetic neuropathy most often affects the lower extremities and may be severe if inadequately treated. Blood glucose control is a critical treatment element, and several medications have been demonstrated to be effective in treating Diabetic Peripheral Neuropathy (DPN), including antiepileptic drugs, antidepressants and opioid analgesics. These medications are often limited by incomplete pain relief and side effects. This is a randomized (study medication is assigned by chance), double-blind (neither the Investigator or the patient know the name of the assigned study medication), placebo-controlled, crossover, parallel-group, multicenter study to determine the effectiveness and safety of 200 mg of RWJ-333369 given twice daily by mouth for 4 weeks compared with placebo in patients with DPN. The study hypothesis is that 200 mg of RWJ-333369 given twice daily by mouth for 4 weeks will be more effective than placebo in reducing pain due to DPN, as measured by average daily DPN pain scores. Patients will receive 200 mg of RWJ-333369 or matching placebo tablets, given in equally divided doses twice daily by mouth with or without food, for 4 weeks in each of the 2 treatment periods.