Patient Education

Diabetic Peripheral Neuropathy

Description

The next time you get a blister, stub your toe into the corner of your dresser, or step on one of those little plastic building bricks, you might wish that your foot was not able to feel anything at all. But the truth is that having little or no feeling in your feet can cause a whole host of problems.

People with diabetes are especially prone to nerve damage (neuropathy), although this damage can also be caused by excessive alcohol, AIDS, and other disorders. Because the ends of long nerves tend to be affected first, the extremities of the body such as hands and feet are usually the first to show symptoms. While it’s not certain what exactly causes this nerve damage, it’s likely that it has something to do with high blood sugar levels. Because diabetics are either not able to produce insulin (a hormone that helps the body process sugar), or their tissues don’t respond to the insulin that’s produced, the levels of sugar in their blood (unless tightly controlled) may become abnormally high, causing damage to blood vessels and nerves.

There are three types of nerves, and each is affected by this diabetic peripheral neuropathy.

  • The first group, and possibly the one you thought of first, is made up of sensory nerves. These nerves are able to feel touch, temperature, pain, and so on. As these nerves become damaged, patients may lose their ability to perceive hot and cold, sharp and dull objects, and may even completely lose all sense of touch in the foot. With this loss of sensation, patients may be unable to feel when their feet are becoming irritated or have been injured. They may continue walking on the injured foot and will fail to seek treatment for the injuries they’re unaware of. This may result in ulcers, Charcot’s foot, or other difficulties. As nerves become damaged, some people may also experience an increase in pain (usually burning or tingling sensations) which can become quite severe.
  • Autonomic nerves help control body functions we don’t think about, such as sweating, heart rate, digestion, etc. As these nerves are damaged, the feet may lose their ability to produce oils and sweat, and may become dried out. Dry skin can crack, resulting in infections, which can become quite serious since diabetics also tend to have problems with healing.
  • Motor nerves control the movement of muscles and muscle tone. When these nerves lose their function, the foot may become deformed or distorted because the muscles holding everything in place are weakened. Bunions and hammertoes may develop, and corns and calluses may show up where the pressure on the foot has changed, or where shoes begin to rub the foot in unusual areas. These can turn into ulcers and become infected.

Sores on your feet may not seem like a big deal, but people with diabetes have trouble healing (due to poor circulation caused by blood vessel damage). Without proper care (and unfortunately, sometimes with it), sores or infections can easily become larger and spread, resulting in gangrene (tissue death), possible amputations of the foot or leg, and sometimes even death.

This is why early detection of problems is so important in patients with neuropathy. If issues are caught early on, they’re much more likely to respond to treatment, thus avoiding amputation.

Of course, the first step in all of this is to try to prevent nerve damage in the first place. To that end, people with diabetes should monitor their blood sugar level closely and keep it in target range. Because once nerves are damaged, there’s no known cure. Neuropathy usually shows up in patients with poorly managed blood sugar levels, but all people with diabetes are still at risk. If you have diabetes, discuss any symptoms you may experience with your doctor, who can help you form a treatment plan.

Symptoms

Neuropathy comes on gradually, and patients may be affected by it before they even discover they have diabetes. This condition may manifest itself in different ways, depending on the type (or types) of nerves that are affected.

  • Sensory nerve damage often starts as a numb feeling or tingling sensation in the feet. These sensations usually begin at the toes and, as the nerve damage gradually progresses, they work their way up the foot and into the ankle. Some people may also experience burning or sharp prickly pain in their feet and legs. Once the feet have become numb, it may feel as though you’re wearing socks, even when you’re not, or you may feel as if you’re walking on cotton or a water-filled cushion. Unless you’re taking a stroll over your waterbed at the time, you should discuss these sensations with your doctor. You may also find it rather harder to walk, since you can’t quite tell where your feet are. You may even change the way you walk (widening your stance or dragging your feet), without realizing it as you try to compensate for your change in sensation.
  • Autonomic neuropathy may manifest itself as dry skin on your feet. The skin over the heel or calluses may become particularly prone to cracking.
  • Damage to the motor nerves may result in weakness or a loss of tone in the lower legs or feet. You may find it harder to keep your balance, and again, may make unconscious compensations for it while walking. As the muscles of your foot weaken, the shape of your foot may also change, possibly resulting in the formation of bunions, hammertoes, or other deformities.

Diagnosis

If you suspect that you may be experiencing neuropathy, even if you don’t think you have diabetes (but especially if you do have diabetes), go see your foot doctor as soon as possible. He or she will likely make the diagnosis by taking your medical history, discussing your symptoms with you, and performing a physical exam. He or she may also use a number of different tests to check your nerve function. These tests may include the filament test, in which a monofilament (a soft nylon fiber) is placed or brushed against the foot. If you’re unable to feel it, you may have nerve damage. Some doctors also use nerve conduction studies, which measures how quickly your nerves carry electrical signals. Electromyography (EG) tests the electrical discharges produced in your muscles, and quantitative sensory testing measures your ability to feel vibrations and hot and cold sensations. Your doctor may also choose to perform autonomic testing which tests your blood pressure or ability to sweat.

Treatment

Unfortunately, there is no known cure for peripheral neuropathy, so once the damage has been done to your nerves, it’s impossible to reverse. The bulk of the treatment, then, focuses on prevention, both of further damage to the nerves and of problems associated with neuropathy, although there are medications available to ease symptoms if they are painful. Oral pain relievers are often used, or sometimes antidepressants or anti-seizure medications are prescribed to treat pain from damaged nerves.

  • Preventing further nerve damage
    • In order to prevent, as much as possible, further damage to your nerves, it’s necessary that you keep your blood sugar level under firm control. Your doctor can best assist you with finding your target range, but for the most part, target blood glucose level ranges are between 70 and 130 mg/dL (or 3.9 to 7.2 mmol/L) before meals, and less than 180 mg/dL (or 10 mmol/L) two hours after a meal.
    • You’ll also want to take an A1C test at least twice a year (more if you have trouble controlling your blood sugar level or have had a change in your medications). This test measures how much sugar has attached to the hemoglobin (the substance that carries all that oxygen around) in your blood. If your average blood sugar level has been low, your A1C number will be lower. However, if your average blood sugar level has been high, your A1C number will rise. In essence, it tests your average blood sugar level for about the past two or three months. When tested, the number should be less than 7%. (People without diabetes tend to average 4 to 6%.)
    • Other preventive measures include keeping your blood pressure under control (diabetic patients frequently also suffer from high blood pressure), maintaining a healthy weight (including following a diet plan discussed with your doctor as well as frequent exercise), and avoiding smoking and the consumption of alcohol.
  • Preventing foot problems
    • First of all, be sure to get to know your local podiatrist. Schedule appointments at least twice a year, and let him or her know you have diabetes. Frequent screening for foot issues can catch minor problems before they become crises. Also, see your doctor immediately if you experience any warning signs, such as redness, swelling, bruising around or under calluses, blisters, cracks, cuts, or feet that have changed shape or feel unusually warm or hot to the touch. (It’s also a good idea to go in if, for instance, you find a tack stuck in the bottom of your foot.)
    • Inspect your feet every day. Check for the warning signs above, especially around the sole of your foot. If you can’t reach your foot or see it very well, use a mirror or ask a friend or family member to help you out. (They’ll get good karma and you’ll get an inspected foot, so it’s a pretty good deal all around.)
    • Wash your feet daily. Use water that’s lukewarm, not hot (test the water with a sensitive part of your skin, such as your elbow, or wet a cloth and put it against your face), and don’t soak your feet unless your doctor instructs you to. Gently dry your feet with a soft towel, paying particular attention to the space between your toes. (You want to avoid fungal infections, which are always ugly things but can be even worse if you have diabetes.) If the skin of your feet is dry, apply a thin film of moisturizer (Cetaphil cream is recommended), although again, avoid getting it between your toes.
    • Wear shoes that fit well. You should never have to break in a pair of shoes, so don’t buy anything that feels uncomfortable when you first wear it. Choose shoes with a generous toe box (about 3/4″ of space between your big toe and the front of the shoe), and flexible, breathable uppers (leather is best) that fully cover your feet. Never wear high heels, sandals, slippers, or other shoes with open toes or heels (especially the kind with the thong between the toes). Running or walking shoes often work best (New Balance brand is recommended). Always check the insides of your shoes for rough lining, seams, or foreign objects (like that plastic toy soldier your child dropped earlier). And avoid socks or stockings with seams, since these can cause irritation to your feet.

It’s true that once you’ve developed neuropathy, there are a lot of things to keep in mind, and there may be a lot of changes to make. It can seem pretty intimidating, in fact, and even discouraging. But the truth is that many people have experienced and are experiencing the same thing, and would likely be willing to talk to you and offer advice, or just sympathize.

And the good news is that following your doctor’s guidelines can really help a lot. While problems do sometimes still develop, even when you’re doing everything right, they’re much, much less likely. So, with a bit of adjustment (and a wee bit of luck), you should be able to live a normal, healthy, and long life.