What is Diabetic Neuropathy?
Diabetic neuropathy is a type of nerve damage that is a common complication if you have diabetes. High blood sugar (glucose) can injure nerve fibers throughout your body, but diabetic neuropathy most often damages nerves in your legs and feet.
Depending on the affected nerves, symptoms of diabetic neuropathy can range from pain and numbness in your extremities to problems with your digestive system, urinary tract, blood vessels and heart. For some people, these symptoms are mild, but for others it can be painful, disabling and even fatal.
You can often prevent diabetic neuropathy or slow its progress with tight blood sugar control and a healthy lifestyle.
What are the Causes?
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. In addition, it weakens the walls of the small blood vessels (capillaries) that supply the nerves with oxygen and nutrients.
Other Factors Include:
- Inflammation in the nerves caused by an autoimmune response. This occurs when your immune system mistakenly attacks part of your 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.
What are the symptoms?
There are four main types of diabetic neuropathy, and each has corresponding symptoms. You may have just one type or symptoms of several types. Most develop gradually, and you may not notice problems 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. Your feet and legs are often affected first, followed by your 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:
- 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 swallowing
- Erectile dysfunction in men
- Vaginal dryness and other sexual difficulties in women
- Increased or decreased sweating
- Inability of your body to adjust blood pressure and heart rate, leading to sharp drops in blood pressure after sitting or standing that may cause you to faint or feel lightheaded
- Problems regulating your body temperature
- Changes in the way your eyes adjust from light to dark
- Increased heart rate when you’re at rest
Radiculoplexus neuropathy (diabetic amyotrophy)
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 your 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, which may be in the face, torso or leg. Mononeuropathy, also called focal neuropathy, often comes on suddenly, and is 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:
- Difficulty focusing your eyes, double vision or aching behind one eye
- Paralysis on one side of your face (Bell’s palsy)
- Pain in your shin or foot
- Pain in your lower back or pelvis
- Pain in the front of your thigh
- Pain in your chest or abdomen
Sometimes mononeuropathy occurs when a nerve is compressed. Carpal tunnel syndrome is a common type of compression neuropathy in people with diabetes.
Signs and symptoms of carpal tunnel syndrome include:
- Numbness or tingling in your fingers or hand, especially in your thumb, index finger, middle finger and ring finger
- A sense of weakness in your hand and a tendency to drop things
When to see a Doctor
Seek medical care if you notice:
- A cut or sore on your foot that doesn’t seem to be healing, is infected or is getting worse
- Burning, tingling, weakness or pain in your hands or feet that interferes with your daily routine or your sleep
- Changes in your digestion, urination or sexual function
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.
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 your foot. Early treatment can help prevent this from happening.
What are the Treatments?
Diabetic neuropathy has no known cure. Treatment for diabetic neuropathy focuses on:
- Slowing progression of the disease
- Relieving pain
- Managing complications and restoring function
Slowing Progression of the Disease
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 you already have. Your doctor will determine the best target range for you based on several factors, such as your age, how long you’ve had diabetes, and your overall health and the presence of other medical conditions.
For many people who have diabetes, the recommended target blood sugar levels are:
- 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
To help slow nerve damage:
- Follow your doctor’s recommendations for good foot care
- Keep your 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:
- Anti-seizure medications. Although drugs such as gabapentin (Gralise, Neurontin), pregabalin (Lyrica) and carbamazepine (Carbatrol, 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 (Norpramin) and imipramine (Tofranil), may provide relief for mild to moderate symptoms by interfering with chemical processes in your brain that cause you to feel pain, but they also cause a number of side effects, such as dry mouth, sweating, weight gain, constipation and dizziness.
- Aerotonin and norepinephrine reuptake inhibitors. For some people, antidepressants called serotonin and norepinephrine reuptake inhibitors (SNRIs), such as duloxetine (Cymbalta), can relieve pain with fewer side effects. Possible side effects of SNRIs include nausea, sleepiness, dizziness, decreased appetite and constipation.
Managing complications and restoring function
Specific treatments exist for many of the complications of neuropathy, including:
- 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 — doctors suggest 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. Your doctor may recommend an abdominal binder, a compression support for your abdomen, and compression stockings. Several medications, either alone or together, may be used to treat orthostatic hypotension.
- Sexual dysfunction. Sildenafil (Revatio, Viagra), tadalafil (Adcirca, Cialis) and vardenafil (Levitra) 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.