Patients with painful diabetic neuropathy (PDN) often combine with anxiety and depression. However, the pathogenesis of PDN is unclear, especially the mechanism associated with central nervous system. The investigators used fraction Amplitude of Low Frequency Fluctuation (fALFF) and Regional Homogeneity (ReHo) of resting-state functional Magnetic Resonance Imaging (rs-fMRI) to explore the brain activity in patients with PDN in order to study the central mechanism.The investigators evaluated the symptoms, signs and mental conditions of patients with PDN and non-pain neuropathy. The brain Blood Oxygen Level Dependent (BOLD) fMRI scan was performed in patients together with some gender and age matched healthy controls. Maybe this study can find that patients with PDN have abnormal brain activity, indicating central nervous system may contribute to painful diabetic neuropathy.

Inclusion Criteria:

• Voluntary participation and signing informed consent
• 18 to 60 years old with junior high school education or above
• meeting the 1999 WHO type 2 diabetes diagnostic criteria: having symptoms of diabetes (polydipsia, polyphagia, polyuria and unexplained weight loss) plus one of the following 3 items: (1) random blood glucose more than 11.1 mmol/L; (2) fasting blood glucose more than 7 mmol/L; (3) after 2 hours glucose load, the blood sugar more than 11.1 mmol/L
• The diagnosis of diabetic peripheral neuropathy (at the same time meets the following three items, of which painful neuropathy patients have pain symptom): (1) neuropathy occurs not earlier than the diagnosis of diabetes; (2) having clinical manifestations of pain, numbness, and abnormal sensation; (3) any abnormality in the following 5 examinations: ankle reflex, vibratory sensation, pressure sensation, temperature sensation, and acupuncture pain

Exclusion Criteria:

• left-hand writers
• neuropathy caused by other causes, such as cervical spondylosis, cerebral infarction, Green Barre syndrome; severe arteriovenous disease; neurotoxic changes caused by drugs and renal insufficiency
• patients with severe cerebral vascular disease
• diagnosed mental disorders such as depression, anxiety and Alzheimer's disease
• patients who can't accept head magnetic resonance imaging, such as those with metal (stents, metal dentures, internal fixation plates, etc.), and claustrophobic space phobias

Meet the diagnosis of diabetic peripheral neuropathy (at the same time meets the following three items, of which painful neuropathy patients have pain symptom): (1) neuropathy occurs not earlier than the diagnosis of diabetes; (2) having clinical manifestations of pain, numbness, and abnormal sensation; (3) any abnormality in the following 5 examinations: ankle reflex, vibratory sensation, pressure sensation, temperature sensation, and acupuncture pain.