WHAT IS DIABETIC NEUROPATHY?

Diabetic neuropathies are neuropathic (nerve) disorders that are associated with diabetes mellitus. Diabetes is a group of metabolic diseases caused by the malfunction of the pancreas. The pancreas is responsible for producing proper amounts of the hormone insulin, which causes cells in the liver, skeletal muscles, and fat tissue to absorb glucose (sugar) from the blood.
If the pancreas secretes little or no insulin (type 1 diabetes), or produces too little insulin or has become resistant to insulin’s action (type 2 diabetes), the level of sugar in the bloodstream increases because it is unable to enter cells. Left untreated, the blood sugar accumulates and produces osmotic stresses on cells by drawing water into the cells. This microvascular injury involving small blood vessels that supply nerves, in addition to abnormal macrovascular conditions, cause sensations such as pain, numbness, tingling and burning. Diabetic neuropathy can affect peripheral nerves including pain fibers, motor neurons and the autonomic nervous system. It therefore can affect all organs and systems, as all are supplied with nerves.

Diabetic neuropathy can be categorized into four types: peripheral, autonomic, proximal and focal. Symptoms vary depending on the nerve(s) affected, and usually develop gradually over years.

Diabetic Peripheral Neuropathy
Diabetic peripheral neuropathy most commonly affects the feet and legs. Nerve damage in the feet can result in a loss of foot sensation, increasing the risk that injuries and sores on the feet may go unrecognized due to lack of sensation. Rarely, other areas of the body such as the arms, abdomen and back may be affected.

  • Symptoms of diabetic peripheral neuropathy may include:
  • Tingling
  • Numbness (severe or long-term numbness can become permanent)
  • Burning, stabbing pain (especially in the evening)
  • Pain and weakness when walking
  • Serious foot problems including ulcers, infections, deformities, and bone and joint pain sometimes leading to amputation

In most cases, early symptoms of diabetic peripheral neuropathy will become less when blood sugar is under control. Medications can be taken to help control pain.

To help prevent the complications of peripheral neuropathy:

  • Examine feet and legs daily.
  • Apply lotion if feet are dry.
  • Care for nails regularly (Go to a podiatrist, if necessary).
  • Wear properly fitting footwear and wear them all the time to prevent foot injury.

Diabetic Autonomic Neuropathy
Diabetic autonomic neuropathy (DAN) may affect many organ systems throughout the body (e.g., gastrointestinal [GI], urogenital and cardiovascular). GI disturbances (e.g., constipation, diarrhea, gastroesophageal reflux, indigestion, frequent abdominal pain, nausea, vomiting, anorexia and fecal incontinence) are common, and any section of the GI tract may be affected.
Neurovascular dysfunction resulting from DAN contributes to a wide spectrum of clinical disorders including erectile dysfunction, loss of skin integrity, and abnormal vascular reflexes. Disruption of microvascular skin blood flow and sweat gland function may be among the earliest manifestations of DAN, and lead to dry skin, loss of sweating and the development of fissures and cracks that allow microorganisms to enter. These changes can ultimately lead to the development of ulcers, gangrene and limb loss.
Cardiovascular autonomic neuropathy (CAN) is the most studied and clinically important form of DAN. This serious, chronic complications of diabetes encompasses damage to the autonomic nerve fibers that innervate the heart and blood vessels, resulting in abnormalities in heart rate control and vascular dynamics. Heart disease and stroke are the top causes of death and disability among people with type 2 diabetes. Diabetes increases the risk of developing high blood pressure and atherosclerosis (hardening/narrowing of the arteries), which eventually lead to heart disease.

Symptoms of diabetic autonomic neuropathy may include:

  • Constipation
  • Gastroparesis (partial paralysis of the stomach)
  • Nausea
  • Vomiting
  • Unable to completely empty bladder
  • Bloating
  • Incontinence (leaking urine)
  • Increased urination at night
  • Erectile dysfunction
  • Decrease in vaginal lubrication
  • Decrease in number of orgasms or lack of orgasm
  • Sudomotor dysfunction (sweat glands)
  • Impaired neurovascular function (involving both nerves and blood vessels)
  • Brittle (uncontrolled) diabetes
  • Hypoglycemic autonomic failure
  • Resting tachycardia
  • Exercise intolerance
  • Orthostatic hypotension (dizzy spells upon standing)

Diabetic Proximal Neuropathy
Diabetic proximal neuropathy is one of the most unusual (affecting only 1 percent of diabetics) and debilitating forms of neuropathy, causing severe pain (usually on one side) in the knees, thighs, hips or buttocks. In some cases it may spread to the other side as well. It also leads to profound weakness in the legs. Diabetic proximal neuropathy usually comes on abruptly, and patients are typically wheelchair user and unable to function during the height of their illness. Treatment for weakness and pain are needed and may include medication and physical therapy. During the acute illness, topical anesthetics, capsaicin cream, antiarrhythmics, opioids, and anticonvulsants and tricyclic antidepressants for chronic neuropathic pain may be used. Amitriptyline may be prescribed for nighttime pain. The recovery varies, depending on the type of nerve damage. Though most patients recover and are able to walk again, they are left with weakness in the legs, and muscle wasting is common.

Diabetic Focal Neuropathy
Diabetic focal neuropathy can also appear suddenly, and affects a specific nerve, most often in the head/face, torso or leg, causing muscle weakness or pain.
Symptoms of diabetic focal neuropathy may include:

  • Double vision, difficulty focusing
  • Aching behind one eye
  • Paralysis on one side of the face (Bell’s palsy)
  • Severe pain in a certain area, such as the lower back or leg(s)
  • Chest or abdominal pain that is sometimes mistaken for another condition such as heart attack or appendicitis

Diabetic focal neuropathy is painful and unpredictable. However, it tends to improve by itself over weeks or months and does not tend to cause long-term damage.

Other Nerve Damage Seen With Diabetes
People with diabetes can also develop other nerve-related conditions, such as nerve compressions (entrapment syndromes). Carpal tunnel is a very common type of entrapment syndrome for diabetics, and can cause numbness, tingling, weakness and pain in the hands. Surgery is usually eventually needed to relieve carpal tunnel syndrome.

Prevention and Treatment of Diabetic Neuropathy
Despite advances in the understanding of the pathology of diabetes, efforts to interrupt these processes have been limited. Thus, tight glucose control is at present the only known way to address the underlying problem. Beyond this, treatments aim at reducing pain and other symptoms.
Since nerve damage caused by diabetes occurs over years, everything done every day to manage diabetes goes a long way toward preventing or minimizing diabetic neuropathy.

Tight glucose control
Treatment of early manifestations of sensorimotor polyneuropathy involves improving glycemic control. Tight control of blood glucose can reverse the changes of diabetic neuropathy, but only if the neuropathy and diabetes is recent in onset. Conversely, painful symptoms of neuropathy in uncontrolled diabetics tend to subside as the disease and numbness progress.

Using a glucose meter
Compliance is everything in controlling diabetes and diabetic nerve damage. Patients should commit to those minimum times for checking levels advised by their physicians/clinicians, and consider checking more often. A close look at what is happening to blood sugar levels throughout the day is essential in order to learn how one’s body is working.

Meeting a target

The National Diabetes Information Clearinghouse (NDIC) gives these general guidelines:

Before meals: 90 – 130 mg/dL
One to two hours after starting a meal: less than 180 mg/dL
The diabetic’s physician may have given different numbers based on symptoms of nerve pain and other diabetes complications. It is important to always follow the doctor’s specific advice on the glucose goal that’s right for each individual.

Eating right
A diet that helps treat nerve pain is really no different from a good, healthy, balanced diet. Blood sugar control is the ultimate goal. A good diet outlines what to eat, when to eat, how much to eat, and allows for healthy snacks. While it’s not always easy for diabetics to watch everything they eat, it is important to remember that every bite counts when it comes to good glucose control.

Being active and exercising
The ultimate goal is to be active for 30 minutes on most days. Exercise helps lower blood sugar, so it is an indirect way to help manage diabetes complications like nerve pain—and help keep blood pressure and blood fats under control. Exercise programs should be monitored by a physician. High impact exercises may not be right for someone who has lost sensation in his feet.

Taking the A1c test
This is a key double-check, along with the glucose meter, that shows whether blood sugar is being controlled over time. The A1c test is a simple blood test that measures the average amount of glucose in the blood for the previous 2 to 3 months, and the National Diabetes Information Clearinghouse (NDIC) recommends taking it a minimum of twice a year.

Strict blood sugar control means an average level of A1c of less than 7 percent. If test results are higher than 8 percent, a discussion between patient and physician is in order to discuss blood sugar management. An A1c higher than 7 percent means that there is a greater chance of eye disease, kidney disease and nerve damage.

Some diabetics who have trouble stabilizing and managing their blood sugar level have found success in using an insulin pump. This allows people to match their insulin to their lifestyles, rather than getting an insulin injection and matching their lives to how the insulin is working. Insulin pumps deliver rapid- or short-acting insulin 24 hours a day through a catheter placed under the skin. Some advantages of using an insulin pump instead of insulin injections are:

  • Using an insulin pump means eliminating individual insulin injections
  • Insulin pumps deliver insulin more accurately than injections
  • Insulin pumps often improve A1C
  • Using an insulin pump usually results in fewer large swings in blood glucose levels
  • Using an insulin pump makes diabetes management easier.
  • Insulin pumps allow diabetics to be more flexible about when and what they eat
  • Using an insulin pump can improve quality of life
  • Using an insulin pump reduces severe low blood glucose episodes
  • Using an insulin pump eliminates unpredictable effects of intermediate- or long-acting insulin
  • Insulin pumps allow a person to exercise without having to eat large amounts of carbohydrate

Treating Nerve Pain

Self care
Warm baths and frequent walks, for some people, can relieve mild symptoms of peripheral nerve pain, though they could interfere with healing if cuts or sores are present on the feet. Wearing shoes that fit well and allow toes to move is a must.

Pain medications
The only two drugs approved by the FDA for diabetic peripheral neuropathy are the antidepressant duloxetine (Cymbalta®) and the anticonvulsant pregabalin (Lyrica®). Localized pain can sometimes be relieved with lidocaine patches.
Creams or gels made from lidocaine, a topical anesthetic or from capsaicin, made from crushed chili peppers.
Over-the-counter pain relievers such as aspirin, acetaminophen, naproxen and ibuprofen.
Prescription-strength nonsteroidal anti-inflammatory drugs (NSAIDs)
Opioids
Antidepressants such as amitriptyline, nortriptyline or duloxetine.
Antiseizure medications such as phenytoin (Dilantin®), carbamazepine (Tegretol®), gabapentin or pregabalin

Other Therapies
Anodyne therapy is a treatment that uses infrared light to soothe pain, usually done in a physical therapy office. Surgical decompression of multiple peripheral nerves (called the Dellon procedure) is another alternative method for treating specific types of diabetic neuropathy.
Several integrative therapies have shown to reduce pain and increase quality of life, such as interferential (electrical current) stimulation; acupuncture; meditation; cognitive therapy; and prescribed exercise.

Links and Support
Mayo Clinic http://www.mayoclinic.com/health/diabetic-neuropathy/DS01045

National Diabetes Information
Clearinghouse (NDIC) http://diabetes.niddk.nih.gov/dm/pubs/neuropathies/
American Diabetes Association http://www.diabetes.org/living-with-diabetes/complications/neuropathy/
The Neuropathy Association http://www.neuropathy.org/site/PageServer (see Resources)