The Diabetic Foot
Diabetes is a disease that develops from a lack of insulin production in the body or the lack of the body’s response to insulin. It is a surprisingly common condition affecting 16 million people worldwide. Diabetes affects many areas of the body including the kidneys, eyes, and the feet. People with diabetes are prone to foot problems for two main reasons; peripheral neuropathy and poor circulation.
Peripheral neuropathy is a loss of sensation in the feet. The symptoms tend to progress slowly over the years and are mostly irreversible. It starts in the toes and slowly works its way back toward the leg. Initially the patient may describe a “tingling” sensation in the toes. As the disease progresses the symptoms can vary but the end result is complete numbness.
Peripheral neuropathy is often described as more of a constant nagging sensation versus sharp pain. This nagging sensation often seems to be more intense when the patient tries to sleep. This is because other distractions often minimize the patient’s fixation on the their feet. The physiological process involves the slow erosion of the lining of the nerves by the elevated glucose level in the blood. Patients are unable to feel hot, cold, or pain. These “protective” sensations guard the feet against injury. This loss of protective sensation can result in a relatively minor foot problem such as a blister or ingrown toenail turning into a major problem because the patient can’t feel it.
Peripheral neuropathy doesn’t just affect the sensory nerves but also the motor nerves. Motor nerves are involved in controlling muscles in the foot. With decreased motor function to the intrinsic muscles of the feet, deformities such as bunions and hammertoes develop. Patients with these deformities are at a higher risk of developing blisters and ulcers which for the diabetic can be life threatening.
Another way that peripheral neuropathy is problematic for diabetics is damage to the autonomic nerves. The autonomic nerves are the small nerves that control the sweat glands in the bottom of the feet. These nerves, like the sensory and motor nerves, stop working so the sweat glands stop working. These sweat glands produce oils that help lubricate the skin. As a result diabetics tend to have dry scaly feet. This makes them more prone to develop large cracks in the skin called fissures. These fissures can be an avenue for infection.
Treating Peripheral Neuropathy
Treatment for peripheral neuropathy is difficult. It begins with getting the diabetics blood sugar under control to prevent further progression of the disease. There are a handful of prescription medications used to treat peripheral neuropathy that have mixed results. These include: Cymbalta (Duloxetine), Lyrica (Pregabalin), Neurontin (Gabapentin), Elavil (Amitriptyline), and Metanx.
With diabetes there is a narrowing of the arteries that can lead to decreased blood flow to the feet and toes. This leads to decrease delivery of oxygen and other vital nutrients making it more difficult to heal wounds and the patient is more susceptible to infection. Also, with decreased blood flow when an infection does occur, the antibiotics used to treat the infection can’t get to the site of infection leading to gangrene and often amputation. If the infection spreads to the blood stream, the patient may develop a fever and the infection at this point becomes life threatening.
Symptoms of Poor Circulation
Signs of poor circulation in the legs and feet may include claudication, pain in the legs or buttock that increases with walking but improves with rest. There are also clinical signs to look for in the feet for poor blood flow. These include hair loss on the lower legs and feet and the skin may take on a shiny appearance.
Education and Prevention
With diabetes, prevention is the name of the game. All diabetics should test their blood sugar daily and keep it at an acceptable level. This is the most important thing you can do as a diabetic. Diabetics are notoriously non-compliant, and it is easy to see why. When your blood sugar is elevated there are often few symptoms and no pain. Pain is the main motivating factor people go to the doctor and take care of themselves. It is important to remember, however, that even if you feel fine when your sugar is running high you are doing irreparable damage to your kidneys, nerves, eyes, feet and many other organ systems.
Diabetics should do a self exam on their feet daily. A good time for this is when bathing. While washing your feet be on the lookout for any drainage, redness, swelling, warmth or other changes. The self foot exam is important because diabetics cannot rely on “feeling” a problem in their feet due to potential nerve damage. When taking a bath or soaking your feet make sure to test the water with your hands before putting your feet in the tub. Thermal burns on the feet are a relatively common phenomenon with diabetics. Wear shoes and socks at all times to prevent stepping on something sharp. Lastly, footwear plays a vital role as part of a comprehensive prevention and treatment plan for diabetics. When shopping for shoes there are general guidelines to keep in mind.
- A high, wide toe box. The toe box is where the toes are. A high toe box is good because it will accommodate hammertoes. Also, a higher toe box will more easily accommodate a shoe insert that diabetics often require.
- A firm heel counter for support and stability.
- Removable insole to allow an optional diabetic insert to be inserted.
- A closed toe shoe is preferred over an open toed shoe for protection from falling objects and the weather.
- A velcro or lace up shoe is preferred over a slip on. Slip on shoes are generally more constrictive over the midfoot to allow the show to stay on. This can be problematic over bony protrusion or when swelling occurs. A lace up shoe or Velcro will also allow you to loosen the shoe if necessary.