To detect small fiber neuropathy in patients with possible or established diabetic peripheral neuropathy (DPN) by skin biopsy and explore clinical characteristics and pathological features in Chinese patients with diabetes.

Small fiber neuropathy (SFN) is a subtype of diabetic neuropathy, patients with SFN often manifest as paresthesia of warmth, cold, pinprick and so on, especially affect ed length-dependent area. Skin biopsy is an effective method to diagnose SFN with high diagnostic accuracy. The procedure is simple and minimally, and the wound usually heals within a few days. However, skin biopsy is not widely used in diagnose of SFN in Chinese patients with diabetes. This study is aimed to establish a normal reference range of intraepidermal nerve fiber density (IENFD) in the Chinese population, and to detect SFN in Chinese patients with diabetes by skin biopsy.

Inclusion Criteria:

• Age ≧ 18 and ≦75 years old
• A history of diabetes
• Symptoms of small fiber neuropathy such as pain, paresthesia, acanthesthesia after diagnosed with diabetes

Exclusion Criteria:

• Acute skin infection or injury
• Coagulation disorders
• History of malignant tumor
• Usage of neurotoxic drugs
• Alcohol abuse
• Vascular diseases, e.g. LEASO and stroke
• Infectious diseases, e.g. hepatitis B, HIV, and syphilis
• Metabolic disorders, e.g. hypothyroidism, hyperlipidemia, and amyloid lesions
• Connective tissue diseases
• Nutritional disorders, e.g.vitamin B6 deficiency, and vitamin B12 deficiency
• Other causes of peripheral neuropathy, e.g. lumbar disc herniation, Guillain-Barre Syndrome, and polyradiculopathy

Chinese patients complaining symptoms of neuropathies after diagnosed diabetes.

The demographic and biochemical indicators of this study.