What are the different stages of diabetic foot ulcers?

Recognising the symptoms of diabetic foot ulcers

Diabetic foot ulcers often develop gradually, and early symptoms can be easy to overlook. Initially, the affected area may feel warm, appear red, or show signs of swelling. Some individuals may experience pain or tenderness, while others—particularly those with diabetic neuropathy—might not feel any discomfort at all. As the condition progresses, an open wound may form, often on high-pressure areas like the heel or ball of the foot.

Key symptoms to watch for include:

• Persistent redness or swelling around a specific area of the foot

• A wound that does not heal or continues to worsen over time

• Thickened or calloused skin that eventually breaks down into an ulcer

• Discolouration of the skin or surrounding tissues, which may indicate poor circulation

• Drainage of pus or a foul odour, suggesting infection

• Loss of sensation in the foot due to nerve damage

Daily foot inspections are essential for those with diabetes, as they can help detect early signs before the ulcer becomes severe. If any of these symptoms appear, seeking medical attention quickly can prevent complications.

What causes diabetic foot ulcers?

Diabetic foot ulcers develop due to a combination of underlying health conditions and external factors that make the feet vulnerable to injury. The most common cause is diabetic neuropathy, which reduces sensation in the feet, making it difficult to notice minor cuts, blisters, or pressure sores before they become serious wounds.

Poor circulation, often caused by peripheral arterial disease (PAD), is another major contributor. When blood flow to the feet is restricted, wounds take longer to heal and are more prone to infection. High blood sugar levels also weaken the immune system, making it harder for the body to fight off infections and repair damaged tissue.

Other factors that increase the risk of foot ulcers include:

• Ill-fitting footwear that creates pressure points or friction

• Foot deformities such as bunions, hammertoes, or Charcot foot

• Lack of proper foot hygiene, leading to bacterial or fungal infections

• Smoking, which further reduces circulation and delays healing

Taking preventive measures, such as wearing proper footwear, keeping blood sugar levels under control, and inspecting the feet daily, can significantly reduce the risk of developing ulcers.

How do diabetic ulcers differ from arterial ulcers?

Diabetic foot ulcers and arterial ulcers are both chronic wounds that affect the lower limbs, but they have distinct causes and characteristics.

• Diabetic ulcers are primarily caused by pressure-related injuries combined with neuropathy. They typically form on weight-bearing areas of the foot, such as the heel or ball of the foot. Because many people with diabetes have reduced sensation, these ulcers may not be painful, which can delay treatment.

• Arterial ulcers, on the other hand, result from poor blood supply due to vascular disease. They often appear on the toes, heels, or areas with minimal circulation. Unlike diabetic ulcers, arterial ulcers tend to be extremely painful and have a deep, well-defined appearance with a “punched-out” look.

Treatment differences

Managing diabetic ulcers focuses on offloading pressure from the affected foot, maintaining proper wound care, and controlling blood sugar levels to aid healing. If an infection develops, antibiotics may be necessary, and in severe cases, surgical intervention may be required to remove dead tissue.

For arterial ulcers, improving blood circulation is the main priority. Treatments may include medications to enhance circulation, lifestyle changes such as smoking cessation, or even surgical procedures like angioplasty to restore blood flow. Unlike diabetic ulcers, arterial ulcers are less likely to heal without medical intervention, making early treatment crucial.

If an individual is unsure whether they have a diabetic or arterial ulcer, a healthcare professional can conduct tests, such as checking blood circulation and nerve function, to determine the best course of action.

The stages of diabetic foot ulcers

Stage 1: pre-ulcerative lesions

At the earliest stage, the skin remains intact but may show signs of irritation, redness, or callus formation due to repeated pressure or friction. Areas of the foot subjected to high pressure, such as the heel or the ball of the foot, are most at risk. People with diabetic neuropathy may not feel the discomfort, allowing these lesions to worsen unnoticed. Regular foot checks and proper footwear can help prevent the progression to an open ulcer.

Stage 2: superficial ulceration

At this stage, the outer layers of the skin (epidermis and dermis) break down, forming an open wound. The ulcer may appear as a shallow sore with a red or yellow base. There is usually no involvement of deeper tissues, but infection can set in if not properly treated. Cleaning the wound, offloading pressure, and applying appropriate dressings are key to preventing further deterioration.

Stage 3: deep ulceration

If the ulcer continues to worsen, it extends beyond the skin into the deeper layers, reaching subcutaneous tissue, ligaments, or even tendons. At this stage, the wound is at high risk of infection, which can lead to severe pain, swelling, and pus formation. Medical intervention, such as debridement (removal of dead tissue) and antibiotic treatment, is often required.

Stage 4: tissue necrosis and gangrene

Without prompt treatment, the ulcer can progress to necrosis, where the surrounding tissue begins to die due to lack of blood supply. Gangrene may develop, leading to blackened, foul-smelling tissue. This stage poses a significant risk of systemic infection (sepsis) and may require surgical intervention, including partial foot amputation in severe cases.

How are diabetic foot ulcers treated?

The treatment of diabetic foot ulcers focuses on wound care, infection control, and pressure relief to promote healing and prevent complications. Keeping blood sugar levels stable is essential, as high glucose can slow healing. The wound is cleaned regularly, and moisture-retentive dressings help create an optimal healing environment. In many cases, debridement, the removal of dead or infected tissue, is necessary to prevent infection and encourage new tissue growth. This can be done using sharp instruments, enzymatic treatments, or surgical methods.

Reducing pressure on the affected foot, known as offloading (such as using specialised footwear or mobility aids, is another key aspect of treatment. Specialised footwear, orthotic devices, total contact casts, or walking boots help redistribute weight and prevent further damage. In more severe cases, advanced treatments such as hyperbaric oxygen therapy can improve blood flow and aid recovery. If an ulcer does not respond to conservative treatment, surgical options like wound grafting or vascular procedures may be required. Early intervention is crucial to prevent serious complications such as deep infections or amputation.

Managing and preventing progression

Early detection is crucial in preventing the progression of diabetic foot ulcers. Regular foot examinations, proper wound care, offloading techniques (such as using specialised footwear or mobility aids, and strict blood sugar control can reduce the risk of complications. If an ulcer does not improve with standard care, consulting a specialist for advanced treatment options, such as skin grafts or hyperbaric oxygen therapy, may be necessary.