PROBLEM TO BE SOLVED: To allow recovery of lowered functional of motor and sensory nerves in patients suffering from diabetic neuropathy by using beraprost in combination with a medicine for diabetes. SOLUTION: Treatment of the diabetic neuropathy especially one accompanied by lowering in nervous conduction speed is performed by using (A) beraprost in combination with (B) a medicine for diabetes. As the component B an insulin-containing preparation or a medicine for diabetes for oral use specifi...