A diabetic foot wound may fail to heal because of poor blood circulation, infection, repeated pressure, nerve damage, uncontrolled blood glucose, or a combination of these factors. A wound that remains open, becomes painful, develops discharge or smell, or shows black discolouration requires prompt medical assessment.
Why diabetic foot wounds heal slowly
Healing requires adequate blood flow, control of infection, protection from repeated pressure and a coordinated response from the body. Diabetes can interfere with several of these processes simultaneously.
Peripheral neuropathy may reduce sensation, allowing a blister or small injury to worsen without being noticed. Continued walking places repeated pressure on the wound. High blood glucose may impair immune function and increase susceptibility to infection. Swelling, poor nutrition, kidney disease and other medical conditions can also delay healing.
A wound should therefore be assessed for the underlying causes rather than treated with dressings alone.
Could poor circulation be responsible?
Peripheral arterial disease reduces the delivery of oxygen and nutrients to the foot. Possible warning signs include:
- Calf or thigh pain while walking
- Foot pain at rest, particularly at night
- A foot that feels colder than the other side
- Weak or absent foot pulses
- Pale, blue or black discolouration
- A wound that remains unchanged despite appropriate care
People with diabetic neuropathy may not experience significant pain even when circulation is severely reduced. Therefore, absence of pain does not always mean that the wound is minor.
Assessment may include examination of foot pulses, Doppler waveforms, ankle–brachial index, toe pressure and arterial Doppler ultrasound. CT angiography, MR angiography or catheter angiography may be required when restoration of blood flow is being considered.
Warning signs requiring urgent medical attention
Seek urgent medical assessment if there is:
- Rapidly spreading redness or swelling
- Pus, foul smell or increasing discharge
- Fever, chills, confusion or marked weakness
- New black, blue or dark tissue
- Sudden coldness, numbness or weakness of the foot
- Severe or increasing pain
- A deep wound with exposed tendon or bone
- Rapid deterioration over hours or days
How is the wound assessed?
A complete diabetic-foot assessment commonly includes:
- Wound location, size, depth and surrounding tissue
- Signs of infection
- Blood supply to the foot
- Sensation and peripheral neuropathy
- Pressure points, footwear and foot deformity
- Blood-glucose control and associated medical conditions
Blood tests may be required when infection or systemic illness is suspected. An X-ray may identify gas, foreign material or bone changes. MRI may be considered when deep infection or osteomyelitis is suspected.
No single test answers every question. The findings must be interpreted together with the clinical examination.
Treatment options
Treatment depends on the cause and severity of the wound. It may include:
Pressure relief
Appropriate off-loading reduces repeated pressure and allows the wound to heal. The method must be selected according to the wound location, infection, circulation and the patient’s overall condition.
Infection control
Infected wounds may require antibiotics, drainage or surgical removal of infected and non-viable tissue. Antibiotics are not routinely required for a clinically uninfected ulcer.
Restoration of blood flow
If poor arterial circulation is limiting healing, revascularisation may be considered. Depending on the arterial disease, this may involve angioplasty, stenting or surgical bypass.
Wound care
Treatment may include appropriate dressings, debridement, swelling control and protection of the surrounding skin. Some wounds may require reconstructive procedures after infection and circulation have been addressed.
Diabetes and general medical care
Blood-glucose management, adequate nutrition, smoking cessation and treatment of kidney, cardiac or other medical conditions are important parts of the healing pathway.
What you can do until medical assessment
- Reduce unnecessary pressure and walking on the affected foot.
- Keep the wound covered with a clean, dry dressing.
- Do not walk barefoot.
- Do not cut callus or dead tissue yourself.
- Do not apply acids, herbal preparations or unprescribed chemicals.
- Do not use very hot water or direct heat on a numb foot.
- Continue prescribed diabetes and vascular medicines unless your treating doctor advises otherwise.
- Arrange prompt medical assessment, especially if the wound is worsening.
Key message
A diabetic foot wound that does not heal is often a sign of an unresolved underlying problem such as poor circulation, infection, pressure or neuropathy. Early assessment can identify these factors and allow treatment before the wound becomes more extensive.
Written and medically reviewed by Dr Siddharth Matad
Vascular & Endovascular Surgeon
MBBS, MS, DNB, DrNB Vascular Surgery
DrNB Vascular Surgery Gold Medalist
KMC 99895
Medical disclaimer: This article provides general patient education and does not diagnose an individual condition or replace an in-person medical assessment. Seek urgent medical care for rapidly worsening wounds, spreading infection, black discolouration, sudden coldness or systemic illness.
References
- International Working Group on the Diabetic Foot. Guidelines on the prevention and management of diabetes-related foot disease, 2023.
- American Diabetes Association. Standards of Care in Diabetes—2026: Retinopathy, Neuropathy and Foot Care.
- NICE Guideline NG19: Diabetic foot problems—prevention and management.