A diabetic foot ulcer (DFU) is an open sore that develops on the foot or lower leg of a person with diabetes. This serious condition is a complication of long-term, elevated blood sugar that damages nerves and blood vessels throughout the body. Ulcers often occur on the bottom of the foot or the heel, signifying a serious breakdown of the skin and underlying tissue. DFUs are a significant health challenge and the leading cause of non-traumatic lower limb amputation globally. The lifetime risk of developing an ulcer is estimated to be as high as 25% for individuals managing diabetes.
The Underlying Causes of Diabetic Foot Ulcers
Diabetic foot ulcers result from a combination of two primary physical problems: damaged nerves and poor circulation. This dual pathology creates an environment where minor injuries go unnoticed and fail to heal correctly. The first and most common factor is diabetic peripheral neuropathy, a type of nerve damage that causes a loss of protective sensation in the feet.
Because of this sensory loss, a person may not feel the pain or irritation from a small blister, friction, or excessive pressure inside a shoe. Unnoticed, this constant stress leads to the breakdown of tissue beneath the skin, forming the initial wound. Neuropathy also causes changes in foot structure, such as hammertoes or bunions, which create abnormal pressure points. Additionally, nerve damage impairs sweat gland function, leading to excessively dry, cracked skin that is more susceptible to tearing and injury.
The second factor is peripheral artery disease (PAD), a condition where blood vessels in the legs and feet narrow and harden. This poor blood flow, or ischemia, means that damaged tissue receives insufficient oxygen, nutrients, and immune cells required for wound repair. PAD severely delays the healing process and significantly raises the risk that a minor, superficial ulcer will progress rapidly into a deep infection or tissue death.
Recognizing and Classifying Ulcer Appearance
The visual appearance of a diabetic foot ulcer changes depending on its severity and whether it is infected. In the earliest, or superficial, stage, the ulcer often appears as a shallow crater or a localized area of skin breakdown. These wounds typically form under areas of high pressure, such as the ball of the foot or the heel, and may be preceded by a thick, broken-down callus. The base of this early ulcer is usually pink or red, indicating healthy tissue, with only a small amount of clear drainage.
As the ulcer progresses, it moves into the deep stage, extending through the skin layers and into the subcutaneous tissue, potentially exposing tendons or joint capsules. The wound may have a crater-like appearance with rolled or callused edges. The base of the wound may contain slough, which is yellow, gray, or white dead tissue that must be medically removed for healing to occur.
Signs of a severe, infected ulcer include a foul odor and the presence of purulent, thick, or cloudy discharge. The surrounding skin may show signs of cellulitis, a bacterial infection characterized by pronounced redness, warmth, and swelling. Blackened tissue, known as necrosis or gangrene, indicates tissue death due to lack of blood flow and severe infection. Recognizing these distinct visual cues requires seeking immediate medical attention, as a deep or infected ulcer is an emergency.
Treatment Protocols and Wound Management
The successful management of an established diabetic foot ulcer relies on three coordinated medical actions to promote healing and prevent amputation. The first is offloading, which involves removing all pressure and weight from the ulcer site. This is often accomplished using specialized devices, such as a total contact cast (TCC) or a removable walker boot. Offloading ensures the tissue can recover without the constant stress that caused the initial breakdown.
The second action is debridement, the medical removal of all dead or infected tissue from the wound bed. A specialist performs this procedure to expose healthy tissue, reduce the bacterial load, and stimulate the body’s natural healing response. Following debridement, the wound is managed with advanced dressings, such as hydrogels or foams, chosen to maintain a moist environment optimal for tissue growth.
Finally, infection control is paramount, as many deep ulcers are colonized by bacteria. If infection is suspected, a deep tissue culture is taken to identify the specific microbe before starting antibiotic therapy. Mild infections may be treated with oral antibiotics, while more severe infections affecting soft tissue or bone require systemic, broad-spectrum antibiotics and sometimes surgical intervention. Optimizing blood glucose control is also a fundamental part of treatment, as elevated sugar levels impair the immune system and slow healing.
Daily Strategies for Foot Ulcer Prevention
Preventing diabetic foot ulcers is an active, daily process focused on meticulous self-care and risk management. The most important preventive step is a thorough daily foot inspection, using a mirror to check the entire foot, including the sole and between the toes. This check is necessary to find any small cuts, blisters, red spots, or changes in skin color that could indicate a developing problem.
Feet should be washed daily with lukewarm water and mild soap; soaking should be avoided as it dries out the skin. It is necessary to dry the feet completely, paying special attention to the spaces between the toes to prevent fungal growth. A moisturizing lotion should be applied to the top and bottom of the foot to prevent cracks, but never between the toes, as this traps moisture.
Wearing proper footwear at all times is another preventive measure, meaning walking barefoot should be avoided, even inside the home. Shoes should be comfortable, have a wide toe box, and be professionally fitted to prevent rubbing or pressure points. Toenails should be trimmed straight across to avoid ingrown nails, and any corns or calluses should be addressed by a healthcare professional, not removed at home with harsh tools or chemicals.