Definition and Overview

A foot ulcer is one of the complications of diabetes, a medical condition that affects the body’s ability to efficiently heal wounds. These are sores found on the skin of the feet, usually accompanied by the disintegration of the tissues surrounding the ulcers. Over time, foot ulcers can eat into the epidermis, as well as the subcutaneous fat and dermis. In a majority of foot ulcer cases, patients are also suffering from diabetes mellitus, a metabolic disease that involves high blood sugar levels over a prolonged period.

In its early stages, foot ulcers can be quite painful, especially when the patient walks, runs, or put any pressure on the affected foot. As foot ulcers begin to break out and appear on the skin, they can have a reddish appearance, much like a rash. However, because the patient’s body does not have the ability to heal itself normally and replace the damaged tissues and skin layers, the ulcers can appear like they are eating right into the patient’s feet. When left untreated, foot ulcers can cause serious complications and can lead to the development of necrosis or the death of the tissues of the skin, which results in decreased or even lack of sensations in the lower extremities, especially around the area of the affected foot. Usually, necrosis is also accompanied by swelling and a foul odour reminiscent of decaying flesh.

In the absences of prompt medical treatment, necrosis can result in gangrene, which typically requires amputation to save the life of the patient.

Though foot ulcers can be life threatening if left untreated, they do respond well to treatment.

Causes of Condition

Individuals suffering from diabetes are at a high risk of developing foot ulcers. Diabetes mellitus increases blood sugar levels, prevents proper blood circulation (especially in the lower extremities), and damages the nerves.

High blood sugar levels can damage nerves over time, preventing the patient from feeling sensations and receiving pain signals from the lower extremities. It would be easy to damage the skin, tissues, and muscles in the feet without the patient feeling it. Minor injuries such as small cuts, bruises, and blisters can escalate to being foot ulcers. Diabetic patients cannot avoid aggravating their minor injuries with walking or putting pressure in there because their nerves are not functioning properly. Once these minor injuries worsen, foot ulcers form.

Aside from diabetes mellitus, other conditions can also cause foot ulcers, including the following:

  • Vascular diseases that hinder proper blood circulation in the lower extremities

  • Peripheral arterial disease, a condition that involves the accumulation of fatty deposits lining the arteries, seriously reducing the amount of oxygen-rich blood flowing to the lower extremities.

  • Even in non-diabetics, poor blood circulation can cause a loss of sensation and affect the body’s ability to heal wounds and injuries. Whenever the feet suffer from injuries, the healing process will be slow and feet thus become more prone to ulcers.

There are also factors that can increase an individual’s risk of developing foot ulcers, including the following:

  • Advanced age
  • Smoking
  • Sedentary lifestyle
  • High cholesterol levels in the blood
  • Obesity
  • High blood pressure
  • History of foot ulcer
  • Diabetes patients who have also experienced issues or conditions affecting the eyes or kidneys
  • Having bunions, which put painful pressure on certain parts of the feet
  • Having problems in the way one walks
  • Ill-fitting shoes

Key Symptoms

It is quite easy to spot a foot ulcer. It is a reddish spot, usually resembling a crater, on the skin. They are usually found on the bottom or sides of the feet, and are also common on the tip of the toes. Most of the time, the sore is surrounded by thickened skin, like a border of callus. In the early stages of foot ulcers, the callus border might not be noticeable.

In more serious cases of foot ulcers, the crater in the skin runs very deep, exposing bones and tendons.

In healthy patients, the ulcers can be very painful since their nerves are functioning properly and are able to send pain signals to the brain.

Who to See and Types of Treatment Available

Seeing a general practitioner upon observing signs of foot ulcer is highly recommended. The doctor will assess the depth of the sore, the presence of an infection, or whether the deep issues and bone are affected. If needed, patients who are suffering from diabetes will be referred to an endocrinologist.

Most infections can be treated by a round of antibiotics. Minor surgery to remove dead tissues and pus can also be performed, before dressing the wounds in special dressings made of materials such as hydrocolloids, absorptive fillers, and hydrogel. Casts can also be wrapped around the foot to protect the ulcers from pressure when the patient is walking or standing.

Managing the blood sugar levels and wearing specialty shoes can prevent the reoccurrence of foot ulcers for diabetic patients in the future.


  • American Diabetes Association. Standards of medical care in diabetes -- 2014. Diabetes Care. 2014;37:S14-S80.

  • Brownlee M, Aiello LP, Cooper ME, et al. Complications of diabetes mellitus. In: Melmed S, Polonsky KS, Larsen PR, Kronenberg HM, eds. Williams Textbook of Endocrinology. 12th ed. Philadelphia, PA: Elsevier Saunders; 2011: chap 33.

  • Kim PJ, Steinberg JS. Complications of the diabetic foot. Endocrinol Metab Clin N Am. 2013;42:833-847.

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