Diabetic Neuropathy

Neuropathy is a complication of diabetes that can lead to problems throughout the body. Diabetes can affect nerves that control movement, sensation and other functions.

If you have diabetes, you can develop nerve problems at any time. Sometimes, neuropathy can be the first sign of diabetes. Significant nerve problems (clinical neuropathy) can develop within the first 10 years after a diabetes diagnosis. The risk of developing neuropathy increases the longer you have diabetes. About half of people with diabetes have some form of neuropathy.

Causes diabetic neuropathy

Although the exact causes of diabetic neuropathy are unknown, several factors may contribute to the disorder, including:

High blood sugar (glucose). High blood glucose causes chemical changes in nerves and impairs the nerves’ ability to transmit signals. It can also damage blood vessels that carry oxygen and nutrients to the nerves.
Metabolic factors. In addition to glucose levels, high triglyceride and cholesterol levels are also associated with increased risk of neuropathy. Patients who are overweight or obese are also at increased risk of developing neuropathy.
Inherited factors. There are some genetic traits that may make some people more susceptible to nerve disease than others.

Symptoms and types of diabetic neuropathy

The symptoms of diabetic neuropathy depend on the type of neuropathy and on which and how many nerves are affected.

Focal Neuropathy (Diabetic Mononeuropathy)

This type of diabetic neuropathy affects one nerve at a time, and the symptoms depend on which nerve is affected. For example, it can affect nerves in the chest (thoracic nerves) and cause numbness and pain in the chest wall that mimics angina, heart attack or appendicitis.

Other types of focal neuropathy can cause:

Pain in the thighs.
Severe pain in lower back or pelvis.
Pain in the chest, stomach or flank.
Aching behind the eyes.
Inability to focus the eyes.
Double vision.
Paralysis on one side of the face.
Hearing problems.

Diabetic Polyneuropathy

Diabetic polyneuropathy (DPN) affects multiple peripheral sensory and motor nerves that branch out from the spinal cord into the arms, hands, legs and feet. Typically, the longest nerves — those that extend from the spine to the feet — are affected the most.

DPN can cause:

Unusual sensations (paresthesias) such as tingling, burning or prickling.
Numbness and pain in the hands, legs and feet.
Weakness of the muscles in the feet and hands.
Sharp pains or cramps.
Extreme sensitivity to touch.
Insensitivity to pain or temperature changes.
Loss of balance or coordination, and difficulty walking on uneven surfaces.

Because it inhibits the ability to sense problems, DPN can put a person at risk for injuries of the feet and toes, and lead to the development of ulcers, wounds and chronic infections in the feet. Diabetic Autonomic Neuropathy

Diabetic autonomic neuropathy primarily affects the autonomic nerves that serve internal organs, processes, and systems of the heart, digestive system, sexual organs, urinary tract and sweat glands.

This kind of diabetic polyneuropathy can cause symptoms such as:

Persistent nausea and vomiting.
Diarrhea, constipation.
Sweating abnormalities.
Sexual dysfunction.
Digestive problems.
Low blood pressure.
Impaired perception of pain.
Hypoglycemia.

Proximal Neuropathy (Diabetic Amyotrophy)

Proximal neuropathy is known by many names, and is a relatively rare type of diabetic neuropathy that occurs in about 1% of patients with type 2 diabetes. It tends to affect older adults, and can strike those with recently diagnosed or well-controlled diabetes.

The main symptom is nerve pain that starts in the upper thigh of one leg and can involve the hip and lower back. Weight loss is a symptom in about 35% of patients with proximal neuropathy, and about 18% experience weakness in the affected area in addition to the pain. Rarely, proximal neuropathy can occur in the arm.

As the condition progresses over months, the pain can spread to involve the upper and lower parts of both legs. After several months, symptoms tend to ease up, but patients can be left with lasting disability, including foot drop and recurrence of symptoms.

Complications

Diabetic neuropathy can cause a number of serious complications, including:

Hypoglycemia unawareness.Blood sugar levels below 70 milligrams per deciliter (mg/dL) normally cause shakiness, sweating and a fast heartbeat. But if you have autonomic neuropathy, you may not notice these warning signs.
Loss of a toe, foot or leg.Nerve damage can make you lose feeling in your feet, so even minor cuts can turn into sores or ulcers without your realizing it. In severe cases, an infection can spread to the bone or lead to tissue death. Removal (amputation) of a toe, foot or even the lower leg may be necessary.
Urinary tract infections and urinary incontinence.If the nerves that control your bladder are damaged, you may be unable to fully empty your bladder. Bacteria can build up in the bladder and kidneys, causing urinary tract infections. Nerve damage can also affect your ability to feel when you need to urinate or to control the muscles that release urine, leading to leakage (incontinence).
Sharp drops in blood pressure.Damage to the nerves that control blood flow can affect your body’s ability to adjust blood pressure. This can cause a sharp drop in pressure when you stand after sitting, which may lead to dizziness and fainting.
Digestive problems.If nerve damage strikes your digestive tract, you can have constipation or diarrhea, or both. Diabetes-related nerve damage can lead to gastroparesis, a condition in which the stomach empties too slowly or not at all, which causes bloating and indigestion.
Sexual dysfunction.Autonomic neuropathy often damages the nerves that affect the sex organs. Men may experience erectile dysfunction. Women may have difficulty with lubrication and arousal.
Increased or decreased sweating.Nerve damage can disrupt how your sweat glands work and make it difficult for your body to control its temperature properly.