4. clinically must be diagnosed by the skin slices of diabetic neuropathy patients have been removed after the completion of clinical diagnosis of the specimen,And then the skin slices of the nerve endings of the optical image observation (20 persons):study the technical observation of diabetic patients with skin sections of the nerve endings of the optical image observation: the clinical must be skin slices for the diagnosis of diabetic neuropathy, patients has been taken out after the completion of clinical diagnosis, and then the skin slices of the nerve endings of the light learning image observation.