Diabetic foot

Diabetic foot refers to the conditions that can affect the feet of some people with diabetes, particularly where there is a loss of sensation, poor circulation or deformity. A small wound may go unnoticed and worsen if it continues to be subjected to pressure, which is why early detection is essential.

What is diabetic foot?

The term ‘diabetic foot’ does not describe a single condition, nor does it mean that everyone with diabetes has foot problems.

It is used to group together various diabetes-related problems that can increase the risk of wounds, infections, joint problems or tissue loss.

A person may have a high-risk foot even if there is no wound present yet. This occurs when there is a loss of sensation, arterial disease, deformities, significant calluses or a history of ulcers or amputation.

The term ‘active foot disease’ is used when an ulcer, infection, gangrene or Charcot neuroarthropathy is already present. Distinguishing between these situations allows for tailored check-ups and enables action to be taken before complications arise.

Three processes may occur simultaneously in the diabetic foot

Loss of sensation makes it easier for an injury to go unnoticed. Repeated pressure prevents the affected area from resting and healing. If, in addition, there is poor blood supply to the tissue, the risk of the wound becoming complicated increases.

Causes of diabetic foot

Diabetic foot usually develops as a result of a combination of several factors. Diabetes that has persisted for years can damage the nerves and arteries. However, a specific ulcer does not develop solely because of high blood glucose levels.

Other factors that play a part include the shape of the foot, the way weight is borne, footwear, calluses, minor injuries and the ability to detect an injury in good time.

Loss of sensation

Diabetic neuropathy can reduce the ability to feel pain, pressure, cold or heat. A graze, a burn or an object inside a shoe may go unnoticed. If the person continues to walk and put weight on that area, the damage may worsen.

Neuropathy can also cause tingling, a burning sensation or pain. It is possible to feel neuropathic pain whilst having lost the protective sensation that would normally warn of an injury. Furthermore, it can lead to dryness, cracks, muscle weakness and certain changes in the shape of the foot.

Repeated pressure

Many ulcers develop in areas subject to high pressure, such as the sole, the heel or certain bony prominences. When there is a loss of sensation, a person may continue to put weight on a damaged area without receiving the pain signal that would normally prompt them to rest.

Deformities, calluses and footwear that constricts or rubs can concentrate the pressure even further.

Peripheral arterial disease

Diabetes also increases the risk of peripheral arterial disease. In this condition, the arteries carrying blood to the legs and feet become narrowed or blocked. As a result, the tissues receive less oxygen and nutrients.

Poor circulation hinders healing, increases the risk of tissue loss and can cause an infection to progress more rapidly. Neuropathy and peripheral arterial disease can occur separately or together in the same person.

What symptoms and signs it can cause

A high-risk foot may not cause any obvious discomfort. For this reason, regular examination and direct observation are particularly important where there is a loss of sensation.

Changes that may occur include:

• Tingling, a burning sensation or reduced sensitivity.

• Dry skin, cracks or calluses.

• Changes in the shape of the foot or toes.

• Areas of chafing or redness.

• Blisters or sores.

• Changes in colour or temperature.

• Swelling.

• Nails that are damaging the skin.

An ulcer is a wound in which part of the skin’s surface has been lost. It may be small and superficial or extend into deeper tissues. The absence of pain does not mean that the lesion is minor. This may be because neuropathy has reduced the ability to feel it.

Warning signs

Any new ulcer, broken blister or wound that does not start to improve requires prompt assessment. Immediate attention is required if there are signs consistent with a serious infection, such as fever, general deterioration, purulent discharge or rapidly spreading inflammation.

A cold, very pale, bluish or blackened foot may indicate a serious lack of blood supply and also requires urgent attention. Exposed tendons or bone, intense pain of recent onset or rapid tissue destruction may indicate a deep injury or an advanced complication.

The absence of a fever does not rule out a significant infection, particularly where neuropathy or poor circulation is present.

Charcot foot

Charcot foot is a complication associated with neuropathy in which the bones and joints become inflamed, weakened and may become deformed. It usually begins with a red, hot and swollen foot. Pain may be minimal or bear no relation to the severity of the inflammation.

Sometimes there is no visible wound. It can be mistaken for an infection, a traumatic injury or joint inflammation.

A foot that suddenly becomes hot and swollen in a person with neuropathy requires prompt assessment. Until the cause is established, it may be necessary to reduce weight-bearing and immobilise the limb to prevent further damage.

How is diabetic foot diagnosed?

There is no single test that can diagnose all the problems covered by the term ‘diabetic foot’. The assessment must determine whether there is a loss of sensation, poor circulation, a wound, an infection, a deformity, sustained pressure or damage to deep tissues.

Identifying a high-risk foot

A preventive examination helps identify who needs closer monitoring. The healthcare professional assesses:

• Sensitivity.

• Circulation.

• The skin and nails.

• Deformities.

• Calluses.

• Footwear.

• Gait.

• History of ulcers or amputation.

Associated medical conditions and any potential difficulties in examining or caring for the feet are also taken into account.

Sensory examination

The monofilament is a small, flexible instrument that applies standardised pressure to specific points on the foot. Its purpose is to check whether protective sensation is preserved, i.e. whether the person perceives sufficient pressure to detect a potential injury.

The examination is usually supplemented with another sensitivity test, such as a vibration test.

Circulation assessment

The healthcare professional feels for the pulses in the feet and observes the colour, temperature and condition of the skin. They may also use an arterial Doppler and compare the blood pressure in the ankle with that in the arm.

In some people with diabetes, the arteries are hardened and these measurements may be unreliable. If there are any doubts or a wound is healing poorly, additional tests may be carried out to better assess tissue perfusion. No single measurement can rule out arterial disease in all cases.

Assessment of an ulcer

The assessment of a wound should determine:

• Where it is located.

• How large it is.

• How deep it is.

• Which tissues it affects.

• Whether there is sustained pressure.

• Whether it is infected.

• Is there sufficient blood supply?

• Whether the bone may be affected.

The cause, duration and treatments used are also reviewed.

Assessment of infection

An ulcer may contain bacteria without being infected. Infection is diagnosed primarily on the basis of clinical signs, such as redness, warmth, swelling, pain, purulent discharge or involvement of deep tissues.

In people with neuropathy or poor circulation, these signs may be less obvious. Deep infections, those that progress rapidly, or those accompanied by general deterioration may require hospital admission.

Culture

Not all ulcers require a culture. Where there are signs of infection, a sample may be taken to identify the microorganisms and guide the choice of antibiotic.

The sample should be taken after cleaning the wound and, wherever possible, from deep tissue. A superficial swab may detect bacteria present on the skin that are not the actual cause of the infection.

Possible bone involvement

Infection of the bone is known as osteomyelitis. It is particularly suspected when the ulcer is deep, has been open for a long time, is situated over a bony prominence, or allows the bone to be seen or felt.

The assessment may include a physical examination, laboratory tests, an X-ray and, where doubts remain, an MRI scan.

What is the treatment?

Treatment depends on the depth of the wound, the presence of infection, blood circulation, the pressure exerted on the area and the person’s general state of health. For an ulcer to heal, it is usually necessary to address several factors in a coordinated manner.

Healing an ulcer requires reducing pressure

A dressing protects the wound, but this may not be enough if the person continues to put weight on it. Pressure-relieving devices redistribute the weight and create better conditions for the tissue to heal.

Reducing pressure

Pressure relief involves reducing or redistributing the pressure on the ulcer. This can be achieved using boots, specialised devices, insoles or therapeutic footwear, depending on the location and characteristics of the wound.

The choice also depends on circulation, the presence of infection, balance and the ability to use the device correctly. In many neuropathy-related plantar ulcers, pressure relief is one of the most important components of treatment.

Treating the wound

Local care may include cleaning, removal of devitalised tissue, management of exudate and protection of the skin surrounding the ulcer. Debridement involves removing dead tissue or calluses that hinder healing. It must be tailored to the patient’s circulation and the condition of the wound.

There is no single dressing suitable for all lesions. The choice of dressing depends on the depth, moisture levels, the type of tissue present and the wound’s progress.

Treating infection

Antibiotics are used when there is a clinical infection. They are not recommended for an ulcer showing no signs of infection, with the aim of preventing infection or speeding up healing.

Moderate or severe infections may require intravenous antibiotics, drainage or surgery to remove infected tissue. Antibiotics treat the infection, but do not, on their own, correct pressure or poor circulation.

Ensuring blood flow

Every ulcer requires an assessment of the blood supply to the foot. If there are signs of poor circulation or the wound is not healing as expected, further vascular investigations may be necessary.

Where poor circulation is hindering healing, the Vascular Surgery department may consider an endovascular procedure or bypass surgery to improve blood flow.

Treating general health and complications

Glucose control is part of the treatment, but it does not, on its own, heal an ulcer. Nutrition, kidney function, blood pressure, cholesterol, smoking and other medical conditions that may influence recovery are also assessed.

Some wounds require surgery to drain an infection, remove non-viable tissue, correct a deformity or treat an affected bone. The aim is to preserve as much tissue and function as possible. In certain situations, a well-planned amputation may be the safest option for managing the condition and facilitating rehabilitation.

Progression and potential complications of diabetic foot

Healing depends on the depth of the ulcer, infection, circulation, pressure and the patient’s general health. Some ulcers heal within weeks. Others take several months, require prolonged treatment or additional procedures.

Possible complications include:

• Spread of infection.

• Osteomyelitis.

• Tissue destruction.

• Deformity.

• Gangrene.

• Need for amputation.

Once the wound has closed, the skin has healed, but the factors that contributed to the injury may still be present. For this reason, a healed ulcer is considered a lesion in remission. The risk of a new wound developing remains high and requires prevention and monitoring.

Early and coordinated care reduces the risk of infection, tissue loss and amputation, although not all complications can be prevented.

In which situations is monitoring particularly important?

Monitoring the foot is particularly important when there is:

• Loss of sensation.

• Peripheral arterial disease.

• Significant deformities or calluses.

• Advanced kidney disease.

• Difficulty seeing or reaching the feet.

• History of ulcers.

• A previous amputation.

Extra care should also be taken during periods of immobility, after wearing new shoes for the first time, in the event of changes to the way you walk, or when an acute illness makes it difficult to carry out your usual foot care routine.

Those who have had an ulcer require ongoing monitoring even after it has healed.

How to prevent further injuries

Preventative measures depend on the level of risk. A person with normal sensation does not need the same plan as someone with arterial disease, a deformity or a history of ulcers.

Check

If there is a loss of sensation, it is advisable to regularly check the soles of the feet, the heels, the spaces between the toes and the inside of your shoes. You can use a mirror or ask for help if mobility or vision makes it difficult to carry out the check.

A blister, a deep crack, a wound, a change in colour or an area of chafing that does not improve should be investigated.

Protect

Feet should be washed with lukewarm water and dried thoroughly, especially between the toes. If you have a loss of sensation, it is advisable to check the water temperature using a part of the body that still has sensation or with a thermometer.

Dry skin can be moisturised, but avoid applying cream between the toes if there is excess moisture. You should not walk barefoot, pick at calluses or use chemical products to remove them yourself if you have a high-risk foot.

Nails should be trimmed without cutting too close to the edges. If you experience difficulty, deformity or are at high risk, it is best to seek professional help.

Choosing the right footwear

Footwear must provide sufficient space, protect the foot and not cause pressure or rubbing. It is advisable to check the inside of the footwear before wearing it and to break it in gradually.

Where there is a deformity, loss of sensation or a previous ulcer, therapeutic shoes or insoles designed to redistribute pressure may be necessary.

Which specialists treat diabetic foot conditions

Diabetic foot may require the involvement of various specialists, depending on whether there is a loss of sensation, impaired circulation, an ulcer, an infection or a deformity.

Endocrinologists, together with GPs and nurses, are involved in the prevention, risk assessment and management of factors related to diabetes.

Specialists in angiology and vascular surgery focus particularly on assessing blood flow in the limb and determining whether vascular tests or procedures to improve blood flow are required.

Depending on the nature of the lesion, professionals from the fields of podiatry, infectious diseases, orthopaedics, interventional radiology and nursing teams with experience in complex wounds may also be involved.

At our hospital, we have a Diabetic Foot and Lower Limb Ischaemia Unit, which specialises in the assessment, treatment and follow-up of these patients using a multidisciplinary and personalised approach.

Living with a high-risk foot or an ulcer

An ulcer may require frequent dressings, pressure-relieving devices and temporary restrictions on walking, working or driving. These measures can affect independence, rest, emotional well-being and family life.

Adapting to pressure relief

It is important to receive clear instructions on when to use the device, how to move about and how to reduce the risk of falls. If a boot or pressure-relieving device proves difficult to use, it is advisable to speak to your healthcare team to find a safe alternative, rather than simply stopping using them without guidance.

Maintaining activity where possible

Limiting weight-bearing does not necessarily mean remaining inactive. The team can adapt your mobility, recommend assistive devices and provide guidance on exercise, rehabilitation and returning to work.

The aim is to protect the injury without unnecessarily losing strength, balance or independence.

Coping with the duration of treatment

Healing can be a slow process and may require long-term changes to daily routines. Difficulties in adhering to dressings or weight-bearing restrictions should not be interpreted as a lack of interest. Living arrangements, work, family support and emotional well-being can all influence the treatment.

Sharing these difficulties with the team allows the plan to be adapted and made more realistic. After healing, follow-up care, suitable footwear and regular monitoring help to detect changes before they develop into a new ulcer.