Diabetic neuropathy is a type of nerve damage that can occur in cases of diabetes. High blood sugar can injure nerve fibers throughout the body, but diabetic neuropathy most often damages nerves in legs and feet.
Symptoms of diabetic neuropathy can range from pain and numbness in extremities to problems with digestive system, urinary tract, blood vessels and heart. For some people, these symptoms are mild; for others, diabetic neuropathy can be painful, disabling and even fatal.
Diabetic neuropathy is a common serious complication of diabetes. Yet it is possible to prevent diabetic neuropathy or slow its progress with tight blood sugar control and a healthy lifestyle.
There are four main types of diabetic neuropathy. There may be just one type or symptoms of several types. Most develop gradually, and problems may not be noticed until considerable damage has occurred.
The signs and symptoms of diabetic neuropathy vary, depending on the type of neuropathy and which nerves are affected.
Peripheral neuropathy is the most common form of diabetic neuropathy. Feet and legs are often affected first, followed by hands and arms. Signs and symptoms of peripheral neuropathy are often worse at night, and may include:
- Numbness or reduced ability to feel pain or temperature changes
- A tingling or burning sensation
- Sharp pains or cramps
- Increased sensitivity to touch — for some people, even the weight of a bed sheet can be agonizing
- Muscle weakness
- Loss of reflexes, especially in the ankle
- Loss of balance and coordination
- Serious foot problems, such as ulcers, infections, deformities, and bone and joint pain
The autonomic nervous system controls your heart, bladder, lungs, stomach, intestines, sex organs and eyes. Diabetes can affect the nerves in any of these areas, possibly causing:
Radiculoplexus Neuropathy (Diabetic Amyotrophy)
- A lack of awareness that blood sugar levels are low (hypoglycemia unawareness)
- Bladder problems, including urinary tract infections or urinary retention or incontinence
- Constipation, uncontrolled diarrhea or a combination of the two
- Slow stomach emptying (gastroparesis), leading to nausea, vomiting, bloating and loss of appetite
- Difficulty in swallowing
- Erectile dysfunction in men
- Vaginal dryness and other sexual difficulties in women
- Increased or decreased sweating
- Inability of body to adjust blood pressure and heart rate, leading to sharp drops in blood pressure after sitting or standing that may cause fainting or feeling lightheaded
- Problems regulating body temperature
- Changes in the way eyes adjust from light to dark
- Increased heart rate when at rest
Radiculoplexus neuropathy affects nerves in the thighs, hips, buttocks or legs. Also called diabetic amyotrophy, femoral neuropathy or proximal neuropathy, this condition is more common in people with Type 2 diabetes and older adults.
Symptoms are usually on one side of the body, though in some cases symptoms may spread to the other side. Most people improve at least partially over time, though symptoms may worsen before they get better. This condition is often marked by:
- Sudden, severe pain in hip and thigh or buttock
- Eventual weak and atrophied thigh muscles
- Difficulty rising from a sitting position
- Abdominal swelling, if the abdomen is affected
- Weight loss
Mononeuropathy involves damage to a specific nerve. The nerve may be in the face, torso or leg. Mononeuropathy, also called focal neuropathy, often comes on suddenly. It's most common in older adults.
Although mononeuropathy can cause severe pain, it usually doesn't cause any long-term problems. Symptoms usually diminish and disappear on their own over a few weeks or months. Signs and symptoms depend on which nerve is involved and may include:
Sometimes mononeuropathy occurs when a nerve is compressed. Carpal tunnel syndrome is a common type of compression neuropathy in people with diabetes.
- Difficulty in focusing eyes, double vision or aching behind one eye
- Paralysis on one side of face (Bell's palsy)
- Pain in shin or foot
- Pain in lower back or pelvis
- Pain in the front of thigh
- Pain in chest or abdomen
Signs and symptoms of carpal tunnel syndrome include:
When to see a Doctor
- Numbness or tingling in fingers or hand, especially in thumb, index finger, middle finger and ring finger
- A sense of weakness in hand and a tendency to drop things
Seek medical care if you notice:
These signs and symptoms don't always indicate nerve damage, but they may signal other problems that require medical care. Early diagnosis and treatment offer the best chance for controlling symptoms and preventing more-severe problems.
- A cut or sore on foot that doesn't seem to be healing, is infected or is getting worse
- Burning, tingling, weakness or pain in hands or feet that interferes with daily routine or sleep
- Changes in digestion, urination or sexual function
Even minor sores on the feet that don't heal can turn into ulcers. In the most severe cases, untreated foot ulcers may become gangrenous — a condition in which the tissue dies — and require surgery or even amputation of foot. Early treatment can help prevent this from happening.
Damage to Nerves and Blood Vessels
Prolonged exposure to high blood sugar can damage delicate nerve fibers, causing diabetic neuropathy. Why this happens isn't completely clear, but a combination of factors likely plays a role, including the complex interaction between nerves and blood vessels.
High blood sugar interferes with the ability of the nerves to transmit signals. It also weakens the walls of the small blood vessels (capillaries) that supply the nerves with oxygen and nutrients.
Other factors that may contribute to diabetic neuropathy include:
- Inflammation in the nerves caused by an autoimmune response. This occurs when immune system mistakenly attacks part of body as if it were a foreign organism.
- Genetic factors unrelated to diabetes that make some people more susceptible to nerve damage.
- Smoking and alcohol abuse, which damage both nerves and blood vessels and significantly increase the risk of infections.
Anyone who has diabetes can develop neuropathy, but these factors make one more susceptible to nerve damage:
- Poor blood sugar control. This is the greatest risk factor for every complication of diabetes, including nerve damage. Keeping blood sugar consistently within target range is the best way to protect the health of nerves and blood vessels.
- Length of time one has diabetes. Risk of diabetic neuropathy increases the longer one has diabetes, especially if blood sugar isn't well-controlled.
- Kidney disease. Diabetes can cause damage to the kidneys, which may increase the toxins in the blood and contribute to nerve damage.
- Being overweight. Having a body mass index greater than 24 may increase your risk of developing diabetic neuropathy.
- Smoking. Smoking narrows and hardens your arteries, reducing blood flow to your legs and feet. This makes it more difficult for wounds to heal and damages the integrity of the peripheral nerves.
Diabetic neuropathy can cause a number of serious complications, including:
Tests and Diagnosis
- Loss of a limb. Because nerve damage can cause a lack of feeling in your feet, cuts and sores may go unnoticed and eventually become severely infected or ulcerated — a condition in which the skin and soft tissues break down. The risk of infection is high because diabetes reduces blood flow to your feet. Infections that spread to the bone and cause tissue death (gangrene) may be impossible to treat and require amputation of a toe, foot or even the lower leg.
- Charcot Joint. This occurs when a joint, usually in the foot, deteriorates because of nerve damage. Charcot joint is marked by loss of sensation, as well as swelling, instability and sometimes deformity in the joint itself. Early treatment can promote healing and prevent further damage.
- Urinary Tract Infections and Urinary Incontinence. Damage to the nerves that control bladder can prevent it from emptying completely. This allows bacteria to multiply in bladder and kidneys, leading to urinary tract infections. Nerve damage can also affect ability to feel when one need to urinate or to control the muscles that release urine.
- Hypoglycemia unawareness. Normally, when blood sugar drops too low — below 70 milligrams per deciliter (mg/dL), or 3.9 millimoles per liter (mmol/L) — one develops symptoms such as shakiness, sweating and a fast heartbeat. Autonomic neuropathy can interfere with ability to notice these symptoms.
- Low blood pressure. Damage to the nerves that control circulation can affect body's ability to adjust blood pressure. This can cause a sharp drop in pressure when one stands after sitting (orthostatic hypotension), which may lead to dizziness and fainting.
- Digestive Problems. Nerve damage in the digestive system can cause constipation or diarrhea — or alternating bouts of constipation and diarrhea — as well as nausea, vomiting, bloating and loss of appetite. It can also cause gastroparesis, a condition in which the stomach empties too slowly or not at all. This can interfere with digestion and cause nausea, vomiting and bloating, and severely affect blood sugar levels and nutrition.
- Sexual Dysfunction. Autonomic neuropathy often damages the nerves that affect the sex organs, leading to erectile dysfunction in men and problems with lubrication and arousal in women.
- Increased or Decreased Sweating. When the sweat glands don't function normally, body isn't able to regulate its temperature properly. A reduced or complete lack of perspiration (anhidrosis) can be life-threatening. Autonomic neuropathy may also cause excessive sweating, particularly at night or while eating.
Diabetic neuropathy is usually diagnosed based on symptoms, medical history and a physical exam. During the exam, doctor is likely to check muscle strength and tone, tendon reflexes, and sensitivity to touch, temperature and vibration.
Doctor may also conduct tests that include:
The American Diabetes Association recommends that all people with diabetes have a comprehensive foot exam — either by a doctor or by a foot specialist (podiatrist) — at least once a year. In addition, feet should be checked for sores, cracked skin, calluses, blisters, and bone and joint abnormalities at every office visit.
- Filament Test. Sensitivity to touch may be tested using a soft nylon fiber or cotton.
- Nerve ConductionStudies. This test measures how quickly the nerves in arms and legs conduct electrical signals. It's often used to diagnose carpal tunnel syndrome.
- Electromyography (EMG). Often performed along with nerve conduction studies, electromyography measures the electrical discharges produced in muscles.
- Quantitative sensory testing. This noninvasive test is used to assess how nerves respond to vibration and changes in temperature.
- Autonomic Testing. In case of symptoms of autonomic neuropathy, doctor may request special tests to look at blood pressure in different positions and assess ability to sweat.
Treatments and Drugs
Diabetic neuropathy has no known cure. Treatment for diabetic neuropathy focuses on:
Slowing Progression of the Disease
- Slowing progression of the disease
- Relieving pain
- Managing complications and restoring function
Consistently keeping blood sugar within a target range can help prevent or delay the progression of diabetic neuropathy and may even improve some of the symptoms one already has. Doctor determines the best target range based on several factors, such as age, how long one has had diabetes, overall health and the presence of other medical conditions.
For many people who have diabetes, recommended target blood sugar levels are:
To help slow nerve damage:
- Between 80 and 120 mg/dL, or 4.4 and 6.7 mmol/L, for people age 59 and younger who have no other underlying medical conditions
- Between 100 and 140 mg/dL, or 5.6 and 7.8 mmol/L, for people age 60 and older, or those who have other medical conditions, such as heart, lung or kidney disease
- Follow recommendations for good foot care
- Keep blood pressure under control
- Follow a healthy-eating plan
- Get plenty of physical activity
- Maintain a healthy weight
- Stop smoking
- Avoid alcohol or, if drinking is allowed, drink only in moderation
Several medications are used to relieve nerve pain, but they don't work for everyone and most have side effects that must be weighed against the benefits they offer. There are also a number of alternative therapies, such as capsaicin cream (made from chili peppers), physical therapy or acupuncture, that may help with pain relief. Doctors frequently use them in conjunction with medications, but some may be effective on their own.
Pain-relieving treatments may include:
For some people, antidepressants called serotonin and norepinephrine reuptake inhibitors (SNRIs), such as duloxetine, can relieve pain with fewer side effects. Possible side effects of SNRIs include nausea, sleepiness, dizziness, decreased appetite and constipation.
- Anti-seizure medications. Although drugs such as gabapentin (Gabacap), pregabalin (Lyrica) and carbamazepine (Tegretol) are used to treat seizure disorders (epilepsy), they're also prescribed for nerve pain. Side effects may include drowsiness, dizziness and swelling.
- Antidepressants. Tricyclic antidepressant medications, such as amitriptyline, desipramine and imipramine, may provide relief for mild to moderate symptoms by interfering with chemical processes in brain that cause to feel pain, but they also cause a number of side effects, such as dry mouth, sweating, weight gain, constipation and dizziness.
Managing Complications and Restoring Function
Specific treatments exist for many of the complications of neuropathy, including:
Lifestyle and Home Remedies
- Urinary Tract Problems. Antispasmodic medications (anticholinergics), behavioral techniques such as timed urination, and devices such as pessaries — rings inserted into the vagina to prevent urine leakage — may be helpful in treating loss of bladder control. A combination of therapies may be most effective.
- Digestive Problems. To relieve mild signs and symptoms of gastroparesis — indigestion, belching, nausea or vomiting —eating smaller, more-frequent meals, reducing fiber and fat in the diet, and, for many people, eating soups and pureed foods. Dietary changes and medications may help relieve diarrhea, constipation and nausea.
- Low Blood Pressure on Standing (Orthostatic Hypotension). This is often helped with simple lifestyle measures, such as avoiding alcohol, drinking plenty of water, and sitting or standing slowly. Doctor may recommend an abdominal binder, a compression support for abdomen, and compression stockings. Several medications, either alone or together, may be used to treat orthostatic hypotension.
- Sexual Dysfunction. Sildenafil (Viagra), tadalafil (Cialis) may improve sexual function in some men, but these medications aren't effective or safe for everyone. Mechanical vacuum devices may increase blood flow to the penis. Women may find relief with vaginal lubricants.
These measures can help reduce risk of diabetic neuropathy:
In case of severe neuropathy and decreased sensation in legs, one can participate in non-weight-bearing activities, such as bicycling or swimming.
- Keep your blood pressure under control. People with diabetes are more likely to have high blood pressure than are people who don't have diabetes. Having both high blood pressure and diabetes greatly increases risk of complications because both damage blood vessels and reduce blood flow. Try to keep blood pressure in the range recommended..
- Make healthy food choices. Eat a balanced diet that includes a variety of healthy foods — especially fruits, vegetables and whole grains — and limit portion sizes to help achieve or maintain a healthy weight.
- Be active every day. Daily activity protects heart and improves blood flow. It also plays a major role in keeping blood sugar and blood pressure under control. About 30 minutes of moderate exercise a day at least five times a week is recommended.
- Stop Smoking. Use of tobacco in any form, increases likelihood of death due to heart attack or stroke. Diabetics are more likely to develop circulation problems in feet.
There are a number of alternative treatments that may help relieve the pain of diabetic neuropathy, such as:
- Capsaicin. When applied to the skin, capsaicin cream can reduce pain sensations in some people. Side effects may include a burning feeling and skin irritation.
- Alpha-lipoic acid. This powerful antioxidant is found in some foods and may help relieve the symptoms of peripheral neuropathy.
- Transcutaneous Electrical Nerve Stimulation (TENS). It prevent pain signals from reaching brain. TENS delivers tiny electrical impulses to specific nerve pathways through small electrodes placed on skin. Although safe and painless, TENS doesn't work for everyone or for all types of pain.
- Acupuncture. Acupuncture may help relieve the pain of neuropathy, and generally doesn't have any side effects. Keep in mind that you may not get immediate relief with acupuncture and will likely require more than one session.