Diabetic foot ulcers and gangrene are mainly caused by combined infection on the basis of neuropathy and vascular lesions. Based on the etiology, diabetic foot ulcers and gangrene can be classified as neurologic, ischemic, and mixed. Grading is based on the severity of the condition. The commonly used grading method is the Wagner grading method: Grade 0: risk factors for the development of foot ulcers, no current ulcers. Grade 1: superficial ulcers, clinically free of infection. Grade 2: deeper ulcers, often combined with soft tissue inflammation (cellulitis), without abscesses or infection of the bone. Grade 3: Deep infection with bone histopathy or abscess. Grade 4: Limited gangrene (toe, heel, or dorsal forefoot). Grade 5: Total foot gangrene. Risk factors for diabetic foot include: 1. previous history of foot ulcers; 2. signs of neuropathy (numbness, decreased or absent sensation of touch or pain in the foot) and/or ischemic vasculopathy (pain in the gastrocnemius muscle or coldness of the foot due to exercise); 3. signs of neuropathy (warm feet, non-sweaty skin, muscle atrophy, hawk-like toes, thickened skin at pressure points, very good pulse, good blood filling) and/or （4. other chronic complications of diabetes (severe renal failure or kidney transplantation, significant retinopathy); 5. neurological and/or vascular pathology that is not severe but has severe foot deformities; 6. other risk factors such as decreased vision, orthopedic problems that affect foot function such as knee, hip or crestal arthritis, ill-fitting footwear, etc.; 7. Personal factors, such as poor socioeconomic conditions, old age or living alone, and refusal of treatment and care.