A diabetic foot ulcer is an open sore or wound that appears on the feet in a significant percentage of patients with diabetes.
These appear most commonly on the soles of the feet; however any part of the foot can be affected. Foot ulcers are a serious problem. Many patients with an ulcer could evntually require an amputation. For this reason, diabetes is the leading cause of non-traumatic lower limb amputation.
The main reason why diabetics so often have foot problems, is that poor circulation leads to a lack of feeling in the lower extremities, so something like a blister, which other people would notice on their feet, goes unnoticed by a diabetic. Because of poor circulation, the healing process is also slow.
South African Podiatry Association (SAPA)