Effects of Epalrestat on Peripheral Neuropathy and Central Nervous System in Diabetic Patients

Inclusion Criteria: 1. Patients aged 18 to 65 years (to the date of screening)； 2. A clear history of type 2 diabetes (using the 1999 WHO diabetes diagnostic criteria) with a course of disease \> 6 months; 3. HbA1c \< 7%; 4. Two or more of the following five tests are abnormal: abnormal temperature perception; Nylon wire for hypoesthesia or disappearance of the foot; Abnormal vibration sense; Ankle reflex disappeared; Two or more nerve conduction velocities were reduced; 5. Have not used mecobalamin, epalrestat, lipoic acid or high-dose glucocorticoid in the recent (3 months) period, or have not been involved in other treatment of the same disease within 3 months prior to the study; Exclusion Criteria: 1. Neuropathy caused by other causes, such as cervical and lumbar lesions, cerebral infarction, etc.; 2. With acute metabolic complications of diabetes, such as ketoacidosis, lactic acidosis, diabetes hyperotonic state, etc; 3. Severe cardiovascular and cerebrovascular diseases , pulmonary heart disease or pulmonary insufficiency, renal failure, severe dyslipidemia, poorly controlled hypertension, severe hepatitis. 4. Those with a history of malignant tumor or wasting diseases such as tuberculosis; 5. Contraindications to MRI scanning: such as internal (especially oral) metal implants, claustrophobia, etc; 6. Poor compliance or serious side effects; 7. pregnant female.