Foot Problems and Diabetes

Foot Problems and Diabetes

Summary

Foot problems are one of the major health consequences of diabetes. In fact, diabetes accounts for 67 percent of foot and leg amputations performed in the United States, according to the National Diabetes Education Program. Nerve damage, infections and circulation problems are among the factors involved in diabetic foot disorders.

People with diabetes often suffer from poor blood circulation and nerve damage that result in part from high levels of glucose (blood sugar). When an injury occurs to the foot, many people with diabetes are less likely to feel the injury and more likely to experience slow healing. As a result, injuries to the foot often go unnoticed before they begin to fester and become infected.

Infections in foot ulcers can spread through the rest of the foot and even into bone (osteomyelitis). Sometimes the patient needs a life-saving amputation to prevent further spread of the infection.

Because of these dangers, people with diabetes must be vigilant in protecting their feet. Regular foot examinations, routine foot care and prompt treatment of injuries are vital to preventing major damage to the feet. Treatment options for diabetic foot problems can include antibiotics, antifungals, wound care, oxygen therapy, skin grafts and surgery.

About diabetic foot problems

Diabetes affects many body systems, and foot problems are one of the major health threats faced by people with diabetes. About 67 percent of lower-extremity amputations performed in the United States result from complications caused by diabetes, according to the National Diabetes Education Program.

Three conditions in particular that are associated with diabetes leave patients more vulnerable to serious foot problems:

  • Increased risk of infections. Elevated levels of glucose (blood sugar) can impair the immune system’s ability to fight infections. This slow healing allows time for the skin to break down and ulcerate. Once infection sets in, it can spread throughout the foot and into the bone (osteomyelitis). An unhealed wound can lead to gangrene, the death of tissues. Eventually, patients may have to resort to a life-saving amputation to stop the spread of the infection.
  • Peripheral neuropathy. This type of nerve damage often results in numbness in the legs and feet of people with diabetes. Because diabetic individuals have less feeling in their legs, they are also less likely to recognize an injury when it occurs.
  • Peripheral arterial disease. People with diabetes are at increased risk for the buildup of fatty plaques in their arteries (atherosclerosis). As their arteries become blocked and hardened, blood flow to the legs is constricted. This deprives injured tissues from receiving the oxygen, nutrients and even medications they need to recover.

Although foot problems can be serious, they are also often preventable. It is essential for patients to keep their glucose levels as normal as possible. In addition, patients can greatly reduce their odds of developing serious foot problems by:

  • Performing regular foot inspections and foot care
  • Maintaining good foot hygiene
  • Choosing correct footwear
  • Receiving periodic foot exams

Types and differences of foot problems

Many types of foot problems can be traced to diabetes. These include:

  • Infections. High levels of glucose (blood sugar) hinder white blood cells from killing bacteria, fungi, viruses and parasites. This can significantly delay healing in people with diabetes and heighten the risk of infection in minor sores, cracked skin and other abrasions.
  • Ulcer. Injured or infected sores on the feet can develop ulcers. Left untreated, ulcers slowly destroy layers of the skin and foot tissue, creating a hole. If this goes deep enough, it can infect the bone, a condition called osteomyelitis.

Gangrene. This is the death of body tissue. It is most often caused by a loss of blood flow, particularly to the legs and feet.

Charcot foot. Also known as Charcot’s foot or Charcot joint, it is a condition in which a person with diabetes is unable to correctly position the foot because of joint or soft-tissue destruction. Diabetic individuals with nerve damage may be unaware of the injury and may continue to walk on it, worsening the situation. This can result in a deformed or fractured foot.

Other foot problems. These include:

  • Corns (thickening of the skin from friction or pressure)
  • Calluses (hard, bony tissue that develops around fractured bone)
  • Blisters
  • Ingrown toenails
  • Bunions (painful, inflamed swelling of the bursa at the first joint of the big toe)
  • Plantar warts (warts on the sole of the foot that can cause small holes)
  • Hammertoes (toes flexed permanently downward)
  • Fungal infections, such as athlete’s foot and nail fungus
  • Dry, cracked skin

Left untreated, any of these conditions can progress and cause complications that may require the patient to undergo a foot or leg amputation. This is the surgical removal of a lower limb, often because of poor circulation or an uncontrolled infection that has destroyed skin, muscle and other tissue.

Risk factors and potential causes of foot problems

There are three major triggers for foot problems in people with diabetes:

  • Weakened immunity. Poor control of glucose (blood sugar) can damage the immune system’s ability to fight infections. Elevated levels of glucose (hyperglycemia) can hinder immune cells from reaching the foot to fight invading microorganisms and infections.
  • Peripheral neuropathy. Nerve damage is a common complication of diabetes. It often causes numbness. People with diabetes who suffer from numbness in their feet are less likely to recognize foot problems that arise. Broken foot bones are a particular problem for those with neuropathy. Nerve damage in the feet can also prevent the patient from sensing temperature. Patients are more likely to suffer burns from hot bath water, hot pavement, heating pads, radiators and space heaters.
  • Peripheral arterial disease. People with diabetes are more likely to have abnormal levels of cholesterol and triglycerides, leaving them vulnerable to atherosclerosis. The resulting blockages and hardening of the arteries often impede blood flow. High blood pressure (hypertension), another condition associated with diabetes, can accelerate this process.

The arteries between the knees and feet are frequently the site of such damage. The blockage in these vessels prevents oxygen, nutrients and even medications from getting to the feet to heal ulcers and other conditions. Because of this slow healing, minor cuts and bruises can develop into deep infections that can spread through the foot and into the bone.

In addition, there are several other risk factors that make a person more likely to suffer diabetic foot problems. Diabetic men are more likely to have lower-extremity amputations than diabetic women, according to the National Diabetes Education Program. Other risk factors associated with foot ulcers and amputations include:

  • History of 10 years or more with diabetes
  • Diabetic retinopathy
  • Cardiovascular problems
  • Kidney problems
  • History of skin ulcers
  • History of bunions, corns or calluses
  • Deformed foot bones
  • Thick toenails

Signs and symptoms of foot problems

Signs and symptoms of foot problems vary according to the origin of the problem. Many diabetic foot disorders involve a foot ulcer. These are sores that do not heal and often become infected. The infection can spread through the foot and into the bone.

Early symptoms of a diabetic foot ulcer include:

  • Skin redness
  • Blistering
  • Other skin irritation

In later stages, the ulcer may develop into an open wound that drains fluid. Signs that a foot ulcer has become infected include:

  • Swelling (edema)
  • Redness
  • Pus
  • Fever
  • High levels of glucose (blood sugar)

In addition, there are symptoms associated with specific diabetic disorders that lead to foot problems. They include:

  • Peripheral neuropathy. Symptoms of nerve damage can be either continuous or sporadic. The most common manifestations are:

    • Numbness
    • Tingling
    • Pricking
    • Burning sensation
    • Foot ulcers that are painless

  • People with diabetes who break a bone, twist an ankle or suffer another injury often cannot feel it because of nerve damage. Because they are unaware of the injury, they are likely to continue to walk on the foot. Eventually, this will cause the foot, ankle and leg to become swollen. This condition is known as Charcot foot. Left untreated, it will eventually damage the bones, joints and ligaments of the foot. As a result, the foot can become distorted and deformed.
  • Peripheral arterial disease. People who have circulation problems due to artery blockages may manifest a number of symptoms. These include:

    • Dry skin
    • Hair loss on feet
    • Coldness of skin (to touch) of the feet
    • Redness of feet when hanging down
    • Paleness in feet when raised above the level of the heart
    • Lack of pulse in the feet
    • Claudication (pain and cramping when muscles fail to receive enough blood)

Diagnosis methods for foot problems

A physician will likely conduct a physical examination and obtain a medical history, including a list of symptoms. Diagnosis methods will differ depending on which underlying condition is suspected of causing the foot problem:

  • Peripheral neuropathy. To test for nerve damage, a physician can check the patient’s feet with a tool called a Semmes-Weinstein monofilament. The physician will apply pressure to the feet with these small nylon filaments, and the patient’s ability to feel this pressure will reveal the extent of damage. This test can offer good insight into a patient’s ability to feel injuries that may occur. People with diabetes are advised to receive the test yearly, or more often if advised by the physician. A thorough check of circulation in the feet should also be performed.

    Several other tests may be administered to determine the extent of nerve or muscle damage due to the peripheral neuropathy. These include:

    • Nerve conduction velocity studies. Small electrodes are placed on the arms and legs and an electric current is sent into the nerve. A slow or weak response to the current indicates nerve damage in that area.
    • Electromyography (EMG). Small, thin needles are inserted into muscles and responses are recorded on an EMG machine.
    • Quantitative sensory testing. Various hot, cold and vibrating stimulations are placed on the body to measure sensation.
    • Nerve biopsy or skin biopsy. A sample of nerve or skin tissue is examined to help identify nerve degeneration from neuropathy and confirm specific conditions.

  • Charcot foot. This condition can be diagnosed based on its appearance and x-rays of the foot, which may reveal bone, joint or ligament damage.
  • Peripheral arterial disease. Specially designed blood pressure cuffs can be placed at the thigh, calf, ankle, forefoot and toe to measure the blood flow in those areas. Some physicians may also perform an arteriography, a diagnostic procedure in which dye is injected into the arteries and x-rays and other analysis is used to look for blockages.

Recent research indicates that two innovative tests can find diabetic foot conditions early. Medical hyperspectral imaging (MHSI) and magnetic spectroscopy can detect low oxygen levels in the skin and reduced energy reserves in the foot muscles. If these tests become more available, they may reduce the rate of amputations, according to the researchers.

Treatment options for foot problems

Scrapes, abrasions, blisters and other seemingly minor injuries should be treated promptly. Patients who are unsure if they can treat a minor condition at home should consult their physician. Bacterial infections can be treated with antibiotics, fungal infections with antifungals and other infections with other antimicrobials.

Patients may be referred to a podiatrist or other specialist for treatment of conditions such as bunions or hammertoes.

Foot ulcers can be treated by draining any pus, removing the dead tissue, keeping the area free of pressure and taking antibiotics to kill infections. The U.S. Food and Drug Administration (FDA) has approved the use of the antibiotic ertapenem for diabetic foot infections that do not involve osteomyelitis. This medication, injected once daily, was shown in the SIDESTEP Study of Diabetic Foot Infections to be as effective as an antibiotic that is injected four times a day.

Sometimes patients may need to use crutches or a wheelchair, or stay off the foot while the ulcer heals. Nonremovable casts can improve healing of diabetic foot wounds.

In some cases, wound dressings may be used to protect the ulcerated skin. A product known as a skin substitute also may be used to help close ulcers. These contain human cells known as fibroblasts that are gradually absorbed into the wound. The cells then grow and replace the damaged tissue in the ulcer.

The FDA has also approved a gel product called becaplermin to treat foot ulcers. This drug contains a protein that encourages tissue growth.  In addition, a topical form of vitamin A may improve healing of diabetic foot ulcers, according to recent research.

Other treatment options available include:

  • Shoes. Charcot foot can be treated by wearing special shoes that help distribute body weight away from the affected area of the foot. In some cases, surgery may be needed to reconstruct the foot and restore its shape.
  • Debridement. This is the removal (by surgery, hydrotherapy or other means) of dead, devitalized or contaminated tissue.
  • Oxygen therapy. Studies have shown that hyperbaric (high-pressure) oxygen can promote healing of diabetic foot wounds and sometimes prevent amputations.
  • Skin grafts. These can be used to help restore the skin damaged by ulcers. 
  • Surgery or other invasive procedures. Bypass operations from above a vascular blockage down into the foot can restore blood flow to the foot. Angioplasty can also open clogged arteries. This is a procedure in which a balloon is inserted into the blood vessel and inflated. This breaks up the plaque and restores blood flow.

Recent research shows that nerve decompression surgery in the foot and leg can reduce pain, enhance sensation and improve balance in people suffering diabetic neuropathy. Other research shows that prompt surgical removal of dead tissue in people with diabetic osteomyelitis can avert more extensive amputation later.

Prevention methods for foot problems

Foot problems are among the most preventable complications of diabetes. However, patients must take an active role in helping to prevent disorders.

It is essential that patients keep their glucose (blood sugar) levels near normal. A good diet, regular exercise and glucose monitoring can help achieve this goal.

Patients should make sure their glucose level is regularly assessed with a glycohemoglobin test to ensure their readings are in the normal range. Quitting smoking will also have a major health impact, as smoking impairs circulation.

There are several other steps patients can take to decrease the odds of suffering foot problems:

  • Foot inspections. It is critical that people with diabetes perform daily foot inspections. Patients should keep the following in mind:

    • Examine the feet every day.
    • Look for blisters, cuts, scratches or cracks in the skin, especially in the heel.
    • Check between the toes.
    • Use a mirror if needed to check the bottom of the feet, or ask a family member or friend to help.
    • Flu-like symptoms or increased glucose (hyperglycemia) can be symptoms of a foot infection. Patients who experience these symptoms should check their feet.

  • Foot hygiene. It is essential to prevent cuts and other wounds from occurring, and to promptly treat them when they do occur. Poor circulation prevents prompt healing, making proper hygiene and care even more important for people with diabetes.

    • Wash feet daily with a mild soap. Dry the feet carefully, paying particular attention to the spaces between the toes.
    • Apply moisturizing cream everywhere except between the toes. Dry skin can become cracked and bleed, which increases the risk of infection. The National Skin Care Institute recommends that people with diabetes use shielding lotions, which preserve moisture, rather than oil-based lotions, which can impede the skin’s creation of natural oils.
    • Trim toenails straight across. Round the edges with an emery board or nail file.  
    • Do not cut corns and calluses. Instead, consult a physician about the best way to treat such abnormalities.
    • See a physician regularly. People with diabetes should have their feet examined by a physician at least four times a year, according to the U.S. Centers for Disease Control and Prevention (CDC). This is especially important for those who have difficulty seeing or who have difficulty trimming their nails. Also, people with diabetes should not try to treat foot problems by themselves, such as attempting to fix an ingrown toenail.
    • Never walk barefoot. It is important to avoid the danger of potentially walking on pins, needles, tacks, glass or other items. Even in the house, it is best to wear slippers or other footwear. Something as minor as stubbing a toe can lead to a foot ulcer.

  • Medical devices. Foot thermometers and many other products are available that may help diabetic individuals reduce their risk of foot problems. For example, clinical trials show that use of special protective insoles and a noninvasive infrared device that monitors skin temperature can prevent 80 percent of foot ulcers and amputations, according to the U.S. National Institutes of Health (NIH). Infrared energy and light devices have been used with diabetic foot problems, but studies have shown mixed results. Patients are advised to ask their physician which devices are recommended and which may be ineffective or even harmful.
  • Footwear. People with diabetes can also reduce the likelihood of suffering foot problems by getting the correct shoes and socks. Shoes should serve four major functions, according to the American Orthopaedic Foot and Ankle Society:
    • Relieve areas of excess pressure. Excessive pressure often leads to ulcers.
    • Reduce shock and shear. Shoes should lessen the vertical pressure on bottom of the foot (shock) and horizontal movement of the foot within the shoe (shear).
    • Accommodate, stabilize and support deformities. Many deformities need to be stabilized to reduce pain and lessen further damage.
    • Limit the motion of joints. Restricting the motion of certain joints can reduce inflammation and pain and result in a more stable foot.

      Patients should also keep the following in mind when buying shoes:

    • Shoes should be comfortable right away. They should not need to be “broken in.” Shoes that cause blistering or calluses should not be worn.
    • Try to wear shoes built for comfort, such as athletic shoes or those with a soft leather upper.
    • Buy shoes at the end of the day, when feet tend to be more swollen. This will ensure that the shoes will be comfortable in all situations.
    • Wear new shoes for an hour around the house. Remove them and check for redness or blisters. For the first week, wear the shoes for longer and longer periods around the house. If the shoes do not feel right at the end of the week, return them.
    • Avoid sandals with thongs between the toes. These can cause gashes in the skin. Also, do not wear shoes or sandals without socks. Other shoes to avoid include clogs, flip-flops and pointy shoes (which squeeze the toes).
    • Change socks daily, and do not wear socks that have holes or have been mended. Some socks are built with extra padding in the heel. These are good options for people with diabetes. Avoid tight socks.
    • Change shoes once a day. By wearing more than one pair of shoes each day, patients can minimize the risk of damaging a spot on the foot that is under pressure from a certain shoe.
    • Before wearing shoes, slip a hand inside and feel for pebbles and other foreign objects.

Questions for your doctor about foot problems

Preparing questions in advance can help patients have more meaningful discussions with their physicians regarding their conditions. Patients may wish to ask their doctor the following questions about foot problems:

  1. Do I have any foot problems, or am I at risk of any?
  2. What diagnostic tests for foot problems might I have to undergo, and what do these tests involve?
  3. What do my test results show?
  4. What is the best treatment for my foot condition?
  5. If medications or other conservative treatments do not work, could I need surgery or other invasive procedures?
  6. How can I prevent other foot problems?
  7. What sort of routine foot care should I perform?
  8. How often should I have a comprehensive foot exam?
  9. What kind of footwear should I use, and what kind should I avoid?
  10. Do you recommend that I use any home medical devices, such as special skin thermometers or insoles?
  11. Should I see a podiatrist or other specialist for nail trimming, treatment of corns, etc.?
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