Definition

Diabetic neuropathy is a complication of diabetes that involves nerve damage. When nerve damage occurs in multiple nerves, it is called polyneuropathy. High blood sugar can injure nerves throughout the body, with diabetic neuropathy most often damaging nerves in the legs. Depending on the affected nerves, symptoms of diabetic neuropathy vary from pain and numbness in the legs to issues with the digestive system, urinary tract, blood vessels, and heart. Some people may have mild symptoms, while others may experience severe pain and limitations in activity.

Diabetic neuropathy is a serious complication of diabetes that can affect about 50% of diabetics. This condition can be prevented or slowed with good blood sugar management and a healthy lifestyle.

Causes

The exact cause of each type of neuropathy is not known. However, researchers have found that over time, uncontrolled high blood sugar can damage nerves and impair their function. High blood sugar also weakens the walls of the small blood vessels (capillaries) that supply oxygen and nutrients to the nerves. This condition is associated with the onset of diabetic neuropathy.

Risk factor

Anyone with diabetes has the potential to develop neuropathy. However, the following risk factors increase the likelihood of nerve damage:

• Poor blood sugar control: Uncontrolled blood sugar increases the risk of all diabetes complications, including nerve damage.
• History of diabetes: The longer you have diabetes, especially if blood sugar is not well controlled, the higher the risk of diabetic neuropathy.
• Kidney disease: Diabetes can damage the kidneys, leading to the accumulation of toxins in the blood, which can cause nerve damage.
• Excess weight: People with obesity are more at risk of developing diabetic neuropathy.
• Smoking: Smoking narrows and hardens the walls of arteries and reduces blood flow to the legs, making wounds difficult to heal and damaging peripheral nerves in the feet.

Symptoms

There are three main types of diabetic neuropathy. Patients may have one or more types of neuropathy. Symptoms depend on the type of neuropathy and the affected nerves. Usually, symptoms develop gradually, and patients may not have complaints until nerve damage is severe.

Peripheral Neuropathy

This type is also known as distal symmetric peripheral neuropathy. It is the most common type of diabetic neuropathy. It typically affects the feet and legs first, followed by the hands and arms. Signs and symptoms include:

• Numbness or reduced ability to feel pain or temperature changes.
• Tingling or burning sensations.
• Sharp pain or cramps.
• Increased sensitivity to touch; for some people, even a blanket on the feet can cause pain.
• Serious foot problems, such as ulcers, infections, and joint and bone pain.
• Symptoms often worsen at night.

Autonomic Neuropathy

The autonomic nervous system controls the heart, bladder, stomach, intestines, reproductive organs, and eyes. Diabetes can affect nerves in any of these areas, causing:

• Unawareness of low blood sugar levels (hypoglycemia).
• Bladder or digestive problems.
• Slow stomach emptying (gastroparesis), causing nausea, vomiting, and loss of appetite.
• Difficulty adjusting vision from light to dark.
• Decreased sexual response.

Proximal Neuropathy (diabetic polyradiculopathy)

This type is also known as diabetic amyotrophy. It often affects nerves in the thighs, hips, buttocks, or legs, and can also affect the abdomen and chest. Symptoms usually occur on one side of the body but may spread to the other side. Symptoms include:

• Severe pain in the hip, thigh, or buttocks.
• Weak and shrinking thigh muscles.
• Difficulty standing up from a sitting position.
• Severe abdominal pain.

Diagnosis

Doctors diagnose diabetic neuropathy through physical exams and by reviewing patient symptoms and medical history. They may check:

• Muscle strength and tone.
• Tendon reflexes.
• Sensitivity to touch and vibration.

Special tests to help diagnose diabetic neuropathy include:

• Filament test: The doctor gently brushes the skin with a fine nylon fiber (monofilament) to test sensitivity to touch.
• Sensory tests: These non-invasive tests measure nerve response to vibration and temperature changes.
• Nerve conduction studies: These measure the speed of electrical signals in nerves of the arms and legs.
• Muscle response tests (electromyography): Often done with nerve conduction studies, these tests measure electrical activity generated by muscles.
• Autonomic tests: These measure how blood pressure changes with different positions and whether you sweat normally.

Management

The management of diabetic polyneuropathy aims to slow disease progression, relieve pain, and manage complications to restore function. Currently, there is no complete cure for diabetic polyneuropathy, but regular and appropriate treatment can improve the quality of life for those affected.

Slowing Disease Progression

Consistent blood sugar control is key to preventing or delaying nerve damage. Good blood sugar management can even improve some symptoms. Doctors will determine the best target range for your blood sugar based on factors such as age, duration of diabetes, and overall health.

Other important steps to slow or prevent worsening neuropathy include maintaining normal blood pressure, keeping an ideal weight, and engaging in regular physical activity.

Pain Relief

Many medications are available for diabetic nerve pain, but they may not work the same for everyone. Consult your doctor to find the most suitable medication for you. Doctors may recommend anticonvulsants or antidepressants for nerve pain relief. Additionally, medications like acetaminophen, ibuprofen, or low-dose medicated patches can help manage pain.

Managing Complications and Restoring Function

You may need care from different specialists, such as a urologist or cardiologist, depending on the complications:

• Urinary problems: Your doctor may suggest stopping or changing medications that affect the urinary tract. Regular urination and gentle pressure on the bladder area may help some urinary problems. Catheter placement might be necessary.
• Digestive issues: For mild gastroparesis symptoms, your doctor may recommend smaller, more frequent meals. Dietary changes and medications can help relieve gastroparesis, diarrhea, constipation, and nausea.
• Orthostatic hypotension: Treatment starts with simple lifestyle changes, such as avoiding alcohol, drinking plenty of water, and changing positions slowly. Elevating the head of the bed about 6 to 10 inches can help prevent blood pressure changes.
• Sexual dysfunction: Medications or injections can improve sexual function in some men but are not safe or effective for everyone. Women may find relief with vaginal lubricants.

Other measures, such as keeping blood pressure under control, eating a healthy diet, quitting smoking, and regular physical activity, can help prevent further complications.

Consult a doctor or physical therapist before starting an exercise program. For those with decreased sensation in their feet, certain activities like walking may be safer than others. If you have a foot injury or pain, continue exercises that do not put weight on the injured foot.

Patients with diabetic neuropathy may have difficulty performing daily activities and are prone to stress. If pain is bothersome, consider consulting a psychotherapist to reduce anxiety. Support groups can also provide advice and support for living with diabetic neuropathy.

Complications

Diabetic neuropathy can cause several serious complications, such as:

• Unawareness of hypoglycemia: Hypoglycemia is indicated by blood sugar levels below 70 mg/dL.
• Loss of toes, feet, or legs: Nerve damage can cause numbness in the feet, so small wounds can become severe without notice.
• Urinary tract infections and urinary incontinence: Nerve damage can prevent complete bladder emptying, leading to bacterial accumulation and UTIs. It can also affect the ability to sense the need to urinate or control the muscles that release urine, causing incontinence.
• Sharp blood pressure drops: Nerve damage affecting blood flow control can impair the body's ability to regulate blood pressure.
• Digestive issues: Nerve damage in the digestive tract can cause constipation or diarrhea. It can also lead to gastroparesis, where the stomach empties slowly, causing bloating and indigestion.
• Sexual dysfunction: Men may experience erectile dysfunction, while women may have issues with arousal and lubrication.
• Excessive or reduced sweating: Nerve damage can disrupt sweat gland function, making it difficult for the body to regulate temperature.

Prevention

You can prevent or delay diabetic neuropathy and its complications by carefully managing your blood sugar and taking good care of your feet.

Blood Sugar Management

The American Diabetes Association recommends that diabetics have an HbA1C test, which measures the sugar attached to red blood cells, at least twice a year. This test shows your average blood sugar level over the past 2-3 months. If blood sugar levels exceed the target, dietary adjustments and medication changes may be needed.

Foot Care

Follow your doctor's advice for proper foot care. Steps to maintain foot health include:

• Daily foot inspection: Check for sores, wounds, bruises, cracked or peeling skin, redness, or swelling. Use a mirror or ask for help to check hard-to-see areas.
• Keep feet clean and dry: Wash feet daily with warm water and mild soap. Avoid soaking feet. Dry feet and between toes thoroughly.
• Moisturize feet: Prevent cracked skin but avoid applying lotion between toes to avoid fungal growth.
• Trim toenails carefully: Cut toenails straight across and file edges gently to prevent sharp edges.
• Wear clean, dry socks: Choose socks made of cotton or moisture-wicking material without tight bands or thick seams.
• Wear well-cushioned, well-fitting shoes: Always wear shoes or sandals to protect your feet. Ensure shoes fit well and provide room for toe movement. A diabetic foot specialist can advise on buying proper footwear and preventing foot issues like calluses.

Nerve disorder screening can also help prevent complications from diabetic neuropathy. The American Diabetes Association recommends that screening for diabetic neuropathy begin immediately after a person is diagnosed with type 2 diabetes and five years after being diagnosed with type 1 diabetes. After that, screening is recommended annually.

When to see a doctor?

Consult a doctor if you have:

• Foot wounds that are infected or not healing.
• Burning, tingling, weakness, or pain in the hands or feet that interferes with daily activities and sleep.
• Digestive, urinary, or sexual function issues.
• Dizziness and fainting.

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