Diabetes predisposes to ulceration of the foot through a variety of processes, including neuropathy and peripheral arterial disease. Once the skin is broken, healing is frequently delayed and the ulcer develops the biology of a chronic wound. The factors underlaying delayed healing in chronic wounds are not well understood but include the effects of repeated trauma, tissue ischemia, infection, defective white cell function, altered immune processes, and altered expression of tissue cytokines and enzymes.