An open sore or wound on the foot in people who have diabetes.

People with diabetes may not notice cuts, bruises or blisters on their feet. That's because diabetes can damage nerves and blood vessels in the feet, so it's harder to feel a foot injury. Diabetes also slows healing. If an injury isn't treated, it may turn into a foot ulcer. Ulcers can lead to serious problems, including foot amputation.

Symptoms of a foot ulcer can include the skin becoming warm and red. The skin also may swell. Fluid or pus may come out of an ulcer. This is called drainage.

Foot ulcers need treatment right away. Treatment might involve removing dead skin and tissue from the ulcer. This is called debridement. Other treatment may include bandages, medicine and surgery. For an ulcer to heal, there can't be pressure on it. Keeping pressure off a foot ulcer may involve using a brace, a cast or special shoes.