Diabetic neuropathy is a nerve disorder caused by diabetes. People who have had diabetes for some time may experience numbness and sometimes pain in their hands, feet and legs.
When I was running a diabetes clinic here in town, one of my first patients was a barber whose neuropathy was so bad that he could not hold scissors or control them at times. If he could not work, he could not afford insurance or treatment for his diabetes and heart condition.
He knew that he had neglected his health for years and that in the present this neglect was haunting him on an almost daily basis and yet he felt trapped. I retell this story because it is important for all of us with diabetes to work on a daily basis to control our blood glucose levels.
This dear man lost everything–his health, his livelihood, and his ability to live a pain free life with any certainty. Nerve damage caused by diabetes can also lead to problems with indigestion ( read our article on gasteoparesis), diarrhea or constipation, dizziness, bladder infections, and impotence.
In my case, neuropathy blocked cardiovascular pain so I did not know I needed open heart surgery. Thank goodness we joined a health club that had a stress test as part of the registration. I was in surgery within 4 days of failing that test.
Who would have thought it? I was in my 40’s, exercised everyday, and was the “diabetes poster woman.” There are treatments and we will bring some research to you in this article, but much research is needed to understand just how diabetes affects the nerves and to find better and more effective treatment for this complication.
People with diabetes can develop nerve problems at any time. Significant neuropathy can develop within the first 10 years after diagnosis and the risk increases the longer you have diabetes.
Research indicates that 60% of people with diabetes have some form of neuropathy, but in 30-40% there are no symptoms. Thirty to forty percent of people with diabetes have symptoms compared to 10% of those without diabetes, Neuropathy is more common in smokers, people over 40 years of age, and people who have difficulty controlling blood glucose levels. The DCCT showed us that after 5 years the risk of diabetic neurology decreased 60% for those in the intensively managed group.
What causes neuropathy?
It is thought that high blood glucose levels causes chemical changes in nerves. This impairs the nerves’ ability to transmit signals. High blood glucose levels also damage blood vessels that carry oxygen and nutriments to nerves.
In addition, inherited factors probably unrelated to diabetes may make some people more at risk than others. Most recently, researchers have all ears on the effects of excessive glucose metabolism on the amount of nitric oxide on nerves. Nitric oxide dilates blood vessels.
In a person with diabetes, low levels of nitric oxide may lead to constriction of blood vessels supplying the nerve, contributing to nerve damage. Another promising area of research centers on the effect of high blood glucose attaching to proteins, altering the structure of the proteins and affecting vascular functioning.
The symptoms of neuropathy depend on which nerves and what part of the body is affected. It can be diffuse, affecting many parts of the body, or focal, affecting a single specific nerve or part of the body. Mild cases may go unnoticed for some time. It may cause pain or insensitivity to pain. It may cause you few problems or it can cause disability.
Diffuse Neuropathy is the first type we will discuss. There are two categories of this category: Peripheral, affecting the feet and hands; and Autonomic, affecting internal organs. Diffuse Peripheral Neuropathy damages the nerves of limbs, especially the feet. Nerves on both sides of the body are affected.
The most common symptoms are numbness or insensitivity to pain or temperature, tingling or burning, sharp pains or cramps, extreme sensitivity to touch, loss of balance, all of which become worse at night.
Diffuse Autonomic Neuropathy
Diffuse Autonomic Neuropathy can affect urination and sexual response. This is a common neuropathy and leads to the bladder being unable to completely empty, Control of the bladder may become a problem. Nerve damage can also lead to a gradual loss of sexual response.
Nerve damage can cause the stomach to empty too slowly a disorder called gastric stasis. Gastroparesis can cause severe illness.
Damage here can cause blood pressure to drop sharply after sitting or standing (orthostatic hypotension). It can also affect the perception of pain from heart disease. Angina may not be able to warn of heart disease and it may also raise the risk of heart attack during general anesthesia. Hypoglycemia may be masked by the inability to sense low blood glucose levels. Sweating may be impaired and therefore it become difficult to control the body’s temperature. Other times, the result of neuropathy may be profuse sweating at night or while eating.
Focal Neuropathy affects specific nerves, most often the torso, leg, or head. It usually appears suddenly and its symptoms can be: pain in the front of the thigh, severe pain in lower back or pelvis, pain in the chest, stomach, or flank, chest or abdominal pain which can be mistaken for angina, heart attack or appendicitis. aching behind the eye, inability to focus the eye, double vision, Bell’s palsy, or trouble hearing.
These tend to occur in older people who have mild diabetes. Although it can be painful, this type of neuropathy tends to improve by itself over a period of weeks or months without causing long-term damage.
Carpal tunnel syndrome
Under focal neurology, we should add that diabetics are prone to developing compression neuropathies. The most common form is carpal tunnel syndrome. Asymptotic carpal tunnel syndrome occurs in 20-30% of those with diabetes, and symptomatic carpal tunnel syndrome occurs in 6-11%.
How is neuropathy diagnosed?
In the doctor’s office a simple nylon filament mounted on a small wand can be used on areas of the foot. It delivers a standardized 10-gram force when the foot is touched. Those who cannot feel this have lost protective sensation and may be at risk for developing diabetic ulcers. Nerve conduction studies can be done. These check the flow of electrical current through a nerve. The impulses are transmitted as an electrical signal. Slower or weaker than usual signals may mean possible damage.
Electromyography (EMG) is used to see how well muscles respond to electrical impulses transmitted by nearby nerves. Ultrasound uses sound waves to image how well the bladder or other parts of the urinary tract are working. Nerve biopsy involves removing a sample of nerve tissue for examination.
Although the symptoms may increase as the control becomes effective, careful long-term monitoring of blood glucose levels helps reverse the pain and loss of sensation that neuropathy can cause. It can also help prevent or delay onset of further problems.
A number of medications are used to relieve the symptoms of neuropathy. An analgesic such as aspirin or acetaminophen, an anti-inflammatory drug containing ibuprofen, antidepressant medications such as amitiptyline, sometimes used with fluphenazine, or nerve medications such as carbamazepine or phenytoin sodium have been used successfully.
Codeine is sometimes prescribed for short-term use to relieve severe pain. Your doctor may prescribe a therapy known as transcutaneous electonid nerve stimulation (TENS). For patients with mild symptoms of slow stomach emptying, doctors suggest eating small, frequent meals and avoiding fats and eating less fiber.
Another important part of treatment involves special care of the feet. These include all of the provisos that we have discussed before including checking the feet daily, proper fitting shoes, using lotions, never going barefoot, cutting toe nails properly, testing water temperature before getting in a tub, and using an emory board to file away dead skin.
If your feet are cold at night, wear socks. Avoid sitting with your legs crossed. Make sure your doctor checks your feet at each visit. If you are unable to care for your feet, ask to be referred to a podiatrist.
What’s in the future?
Several drugs are under study, but not ready for humans yet. One is myoinostol, which is thought to be missing in the nerves of diabetic animals and humans. Supplements increase the levels in research animals.
Another is the drug aminoguanidine which in animals blocks cross-linking of proteins that occur more frequently than normal in tissues exposed to high levels of glucose. ARI’s are a class of drugs that are thought to block the formation of the sugar alcohol sorbitol which is thought to damage nerves. So far clinical trials have shown that these drugs cause major side effects so they are not available for clinical use.
Recent research shows that antidepressants and anticonvulsants have similar efficacy in neuropathic pain, although side effects were more of a problem with the former. The article is in the December Journal of Pain and Symptom Management, by Dr. Henry McQuay. Talk to your doctor about your symptoms. There is help.