Inclusion Criteria:  Patients aged 18 to 65 years (to the date of screening)； A clear history of type 2 diabetes (using the 1999 WHO diabetes diagnostic criteria) with a course of disease > 6 months; HbA1c < 7%; 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; 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:  Neuropathy caused by other causes, such as cervical and lumbar lesions, cerebral infarction, etc.; With acute metabolic complications of diabetes, such as ketoacidosis, lactic acidosis, diabetes hyperotonic state, etc; Severe cardiovascular and cerebrovascular diseases , pulmonary heart disease or pulmonary insufficiency, renal failure, severe dyslipidemia, poorly controlled hypertension, severe hepatitis. Those with a history of malignant tumor or wasting diseases such as tuberculosis; Contraindications to MRI scanning: such as internal (especially oral) metal implants, claustrophobia, etc; Poor compliance or serious side effects; pregnant female.