- Grade 0: No open ulcer; may have pre-ulcerative lesions
- Grade 1: Superficial ulcer without underlying involvement
- Grade 2: Deep ulcer involving skin and subcutaneous tissue
- Grade 3: Ulcer with deep involvement, including bone or abscess
- Grade 4: Gangrene in the forefoot, may require partial amputation
- Grade 5: Extensive gangrene necessitating full foot amputation