Diabetic foot: symptoms, causes and treatment

A diabetic foot is the generic name for chronic foot problems that occur as a result of diabetes. It is not a single condition but a combination of various complications that make your feet vulnerable to wounds and infections. These complications develop gradually over years and can lead to serious problems if not recognized and treated in time.

Diabetes affects your body in various ways, all of which affect your feet. First, the disease can damage your blood vessels through a process called atherosclerosis, or calcification. The arteries that bring blood to your feet can clog up, which reduces blood supply. Poorly circulated tissue heals more difficult and is more susceptible to infections.

Second, diabetes can affect your nerves, a condition called polyneuropathy. Increased blood sugar levels damage the thin blood vessels that supply your nerves with nutrients. This usually starts in your feet and legs because they are farthest from your brain and spinal cord. You then feel less pain, heat, cold or pressure. This nerve disorder has far-reaching consequences. You don't notice small wounds because you don't feel the pain. You may be walking with a pebble in your shoe without even noticing it, or you may be standing on a floor that is too hot without realizing that you are burning yourself. The feeling in your feet also changes, causing you to unconsciously walk differently, leading to changes in your foot position that create more pressure in some places.

This increased pressure causes pressure sores and calluses. Beneath these thick layers of calluses, bruises and eventually sores can form without you even noticing it. In addition, diabetes makes you more susceptible to infections because your immune system works less effectively at high blood sugar levels. The result of all these factors combined is the diabetic foot: a foot that is vulnerable to wounds, has difficulty healing, becomes infected quickly, and may miss important warning signs such as pain.

The development of a diabetic foot is a gradual process that takes place over years. It starts with years of elevated blood sugar levels that damage your blood vessels and nerves. In type 1 diabetes, foot problems usually don't develop before someone has diabetes for more than 15 years and is over 30 years old. The situation is different with type 2 diabetes because this form is often only discovered when someone has had elevated blood sugars for years without knowing it.

The nerve impairment develops gradually: first you lose the ability to feel fine temperature differences, then the sense of pain deteriorates, and eventually you may not be able to feel anything at all in your feet. Due to the nerve damage, certain muscles in your feet no longer work properly, leading to malformations such as hammertoes where the toes are crooked, or flat feet where the arch of the foot disappears. These malformations cause abnormal pressure distributions.

At these pressure points, calluses are created as protection. Beneath this callus, bruises can form, visible as dark blue patches. These are actually a warning sign that there is too much pressure in that area and that the skin is about to break. If the pressure persists, an ulcer eventually develops: an open wound in the skin. Because you don't feel the pain, you just walk on your ulcer, further damaging the tissue each step. Bacteria easily enter through these open wounds and multiply faster because the immune system is less effective. The infection can spread into the surrounding tissue and even reach the bone.

The most prominent symptom is small to larger wounds at the pressure points of your foot. These are usually located on the ball of the foot or on the heel. The wounds heal poorly or not at all despite care. The wound itself often looks unhealthy: the bottom is not red but covered with yellow pus, dirty batter or a hard dark crust. At the wound edge, you can see no signs of recovery. The edges are often inflamed, red, and swollen. Sometimes you can smell an unpleasant smell that indicates a bacterial infection.

In your calluses, you can see dark blue bruises. These are not caused by an impact but by constant pressure from within. Doctors consider these to be a precursor to a foot ulcer. When blood circulation is poor, your feet feel colder than normal. The skin can turn a bluish or purplish color, especially if you've been sitting still for a while. When you let your feet hang, they become redder due to gravity. When you raise them, they actually turn pale.

The nerve damage changes the feeling in your feet. Some people no longer feel pain, heat, or cold at all. Others, on the other hand, experience tingling, burning, or electric shocks. Deformities of your feet develop gradually, such as hammer toes that are permanently crooked or flat feet where the arch of the foot collapses. These changes make it more difficult to find well-fitting footwear.

A special form is Charcot's disease, in which your foot swells acutely. Your foot becomes hot, red, and swollen, sometimes with mild pain. This looks like an infection but is actually an inflammation of the joints and bones. If this is not treated quickly, severe deformities follow because joints and bones are damaged and crumbled.

Diabetic foot problems focus on specific areas where the most pressure and friction occur. The ball of your foot is the most common location for sores. This is the area just behind your toes where you push off when walking. With every step, there is considerable pressure on this area, especially if your foot no longer functions properly due to nerve damage.

The heel is the second most common spot. Your heel supports your entire body weight when you put your foot down. Under the calluses, sores can form that penetrate deeply. The top of your toes, especially hammer toes, is sensitive to pressure caused by shoes. Because the toes are crooked, they rub against the top of your shoe.

The side of your foot can develop sores if your foot is disfigured. In certain foot deformities, the side presses against the inside of your shoe, causing friction. Between your toes, problems can occur due to moisture and friction, leading to infections and wounds. Charcot disease may affect the entire foot, with swelling and deformities often concentrating in the metatarsal area.

The treatment has two goals: to solve current problems and to prevent future complications. In case of an infected wound, your doctor prescribes antibiotics that fight the bacteria. You may first receive this via an infusion in the hospital. In case of fungal infections, the doctor prescribes antifungal medications. It is crucial to complete the entire cure.

In the case of a foot ulcer, your doctor must remove the dead material and the surrounding calluses. This is called debridement. He uses sterile instruments to gently remove all dead cells, dirt and excess calluses until he reaches healthy, bleeding tissue. By removing the dead material, the wound has a better chance of healing.

Pressure relief is essential for healing a foot ulcer. As long as you just keep walking on your ulcer, it can't heal because each step damages the tissue. Your doctor therefore recommends appropriate footwear with special soles that take pressure off the ulcer. In some cases, a running plaster is necessary. This is a cast around your lower leg and foot that allows you to walk while completely relieving the ulcer. After a few weeks or months, when the ulcer has healed, the gypsum can come off.

If the wound does not heal despite good care, your doctor will refer you to a specialist such as a dermatologist, surgeon, or internist who specializes in diabetic feet. More advanced treatments are available at the hospital. If the infection spreads to the surrounding tissue, hospitalization is necessary. If the infection has reached the bone, osteomyelitis develops, a very serious complication that requires weeks of antibiotic therapy and sometimes surgical removal of the infected bone.

Charcot's disease requires a prolonged gypsum immobilization of up to six months. Your foot must rest completely while the bones and joints stabilize. Sometimes surgical correction is necessary where the surgeon repositions the bones and fastens them with pins or plates.

There are several things that people try but are ineffective or even harmful. Self-treatment of wounds without medical advice is risky. Diabetic foot ulcers require professional care. Without proper treatment, the wound will persist and may become infected. Just continuing to get rid of an ulcer is harmful, but with diabetes, you often feel no pain due to the nerve damage. Rest is essential: if you have an ulcer, you should walk on that foot as little as possible.

Shoes that don't fit properly are a major cause of new problems. Without feeling normal, you won't notice that your shoes are pinching until blisters or sores develop. Only wear well-fitting shoes that have been approved by your doctor or podiatrist. Placing hot water bottles, cherry stone pillows, or electric blankets on your feet can cause burns. Due to the reduced sensitivity, you will not notice that it is too hot. Avoid all direct sources of heat on your feet.

Cutting away corns or calluses independently with a razor or scissors is dangerous and can lead to deep cuts that infect. Always have calluses and corns removed professionally by your doctor or podiatrist. Strong, irritating ointments for treating corns are far too aggressive and can cause severe burns. Walking barefoot, even in the home, is unwise. Always wear protective footwear, even indoors. Ignoring your blood sugar levels works against everything. Good diabetes control is the basis of everything.

How often should I check my feet?

You should inspect your feet daily, preferably in the evening after undressing. Look at all sides: top, bottom, sides, between toes and nails. Use a mirror to see the soles of your feet if you can't reach your feet properly. Look for redness, swelling, blisters, sores, cracks, calluses and bruises. If you see anything abnormal, contact your doctor.

Can a diabetic foot heal completely again?

A foot ulcer can heal completely with the right treatment and care, especially if detected early. However, the underlying problems such as nerve impairment and circulatory disorders are usually permanent. This means that you are always at risk of new problems. However, with good prevention and care, you can stay without new sores for years.

Do I have to wear special footwear?

Many people with diabetic foot problems benefit from appropriate footwear. These are shoes that are extra spacious, have soft padding, and possibly have adapted soles that distribute pressure evenly. Your doctor or podiatrist will advise whether this is necessary for you. The costs are often (partially) reimbursed by the health insurer for people at increased risk.

How do I prevent it from getting worse?

Good diabetes control is the most important factor. Keep your blood sugar levels within target levels by taking your medication faithfully and following your diet. In addition, daily foot inspection, good foot care, suitable shoes, and regular check-ups with your doctor or podiatrist are essential. Stop smoking if you smoke, as this significantly worsens blood flow problems.

Do I need to see a podiatrist?

In Belgium, you are entitled to an annual reimbursement of two foot care sessions with a podiatrist if you have diabetes. Take advantage of this. A podiatrist can professionally cut your nails, remove calluses, and treat minor problems before they become big. He or she also advises on suitable footwear and care products.

What if I don't feel pain in my feet?

Decreased feeling in your feet means you have to be extra careful. You don't notice minor injuries, so you should really check daily. Measure the temperature of the bath water with a thermometer before you step in. Inspect your shoes for cracks or objects before putting them on. Be extra vigilant about all the ways you can damage your feet without even noticing it.

1. Skindr dermatologists
2. Health and Science: Treatment of a Diabetic Foot
3. eBPNet (Evidence-Based Practice Network)
4. UZ Leuven: Diabetes and foot problems
5. Thuisarts.nl: Take good care of your feet in case of diabetes
6. Diabetes League Belgium: Foot problems