Diabetic neuropathy is a type of nerve damage that can occur if you have diabetes. High blood sugar (glucose) can injure nerves throughout the body. Diabetic neuropathy most often damages nerves in the legs and feet.
Depending on the affected nerves, diabetic neuropathy symptoms include pain and numbness in the legs, feet and hands. It can also cause problems with the digestive system, urinary tract, blood vessels and heart. Some people have mild symptoms. But for others, diabetic neuropathy can be quite painful and disabling.
Diabetic neuropathy is a serious diabetes complication that may affect as many as 50% of people with diabetes. But you can often prevent diabetic neuropathy or slow its progress with consistent blood sugar management and a healthy lifestyle.
There are four main types of diabetic neuropathy. You can have one type or more than one type of neuropathy.
Your symptoms depend on the type you have and which nerves are affected. Usually, symptoms develop gradually. You may not notice anything is wrong until considerable nerve damage has occurred.
This type of neuropathy may also be called distal symmetric peripheral neuropathy. It's the most common type of diabetic neuropathy. It affects the feet and legs first, followed by the 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
- Tingling or burning feeling
- Sharp pains or cramps
- Muscle weakness
- Extreme sensitivity to touch — for some people, even a bedsheet's weight can be painful
- Serious foot problems, such as ulcers, infections, and bone and joint damage
The autonomic nervous system controls blood pressure, heart rate, sweating, eyes, bladder, digestive system and sex organs. Diabetes can affect nerves in any of these areas, possibly causing signs and symptoms including:
- A lack of awareness that blood sugar levels are low (hypoglycemia unawareness)
- Drops in blood pressure when rising from sitting or lying down that may cause dizziness or fainting (orthostatic hypotension)
- Bladder or bowel problems
- Slow stomach emptying (gastroparesis), causing nausea, vomiting, sensation of fullness and loss of appetite
- Difficulty swallowing
- Changes in the way the eyes adjust from light to dark or far to near
- Increased or decreased sweating
- Problems with sexual response, such as vaginal dryness in women and erectile dysfunction in men
Proximal neuropathy (diabetic polyradiculopathy)
This type of neuropathy often affects nerves in the thighs, hips, buttocks or legs. It can also affect the abdominal and chest area. Symptoms are usually on one side of the body, but may spread to the other side. Proximal neuropathy may include:
- Severe pain in the buttock, hip or thigh
- Weak and shrinking thigh muscles
- Difficulty rising from a sitting position
- Chest or abdominal wall pain
Mononeuropathy (focal neuropathy)
Mononeuropathy refers to damage to a single, specific nerve. The nerve may be in the face, torso, arm or leg. Mononeuropathy may lead to:
- Difficulty focusing or double vision
- Paralysis on one side of the face
- Numbness or tingling in the hand or fingers
- Weakness in the hand that may result in dropping things
- Pain in the shin or foot
- Weakness causing difficulty lifting the front part of the foot (foot drop)
- Pain in the front of the thigh
When to see a doctor
Call your health care provider for an appointment if you have:
- A cut or sore on your foot that is infected or won't heal
- Burning, tingling, weakness or pain in your hands or feet that interferes with daily activities or sleep
- Changes in digestion, urination or sexual function
- Dizziness and fainting
The American Diabetes Association (ADA) recommends that screening for diabetic neuropathy begin immediately after someone is diagnosed with type 2 diabetes or five years after diagnosis with type 1 diabetes. After that, screening is recommended once a year.
The exact cause of each type of neuropathy is unknown. Researchers think that over time, uncontrolled high blood sugar damages nerves and interferes with their ability to send signals, leading to diabetic neuropathy. High blood sugar also weakens the walls of the small blood vessels (capillaries) that supply the nerves with oxygen and nutrients.
Anyone who has diabetes can develop neuropathy. But these risk factors make nerve damage more likely:
- Poor blood sugar control. Uncontrolled blood sugar increases the risk of every diabetes complication, including nerve damage.
- Diabetes history. The risk of diabetic neuropathy increases the longer a person has diabetes, especially if blood sugar isn't well controlled.
- Kidney disease. Diabetes can damage the kidneys. Kidney damage sends toxins into the blood, which can lead to nerve damage.
- Being overweight. Having a body mass index (BMI) of 25 or more may increase the risk of diabetic neuropathy.
- Smoking. Smoking narrows and hardens the arteries, reducing blood flow to the legs and feet. This makes it more difficult for wounds to heal and damages the peripheral nerves.
Diabetic neuropathy can cause a number of serious complications, including:
- Hypoglycemia unawareness. Blood sugar levels below 70 milligrams per deciliter (mg/dL) — 3.9 millimoles per liter (mmol/L) — usually cause shakiness, sweating and a fast heartbeat. But people who have autonomic neuropathy may not experience these warning signs.
- Loss of a toe, foot or leg. Nerve damage can cause a loss of feeling in the feet, so even minor cuts can turn into sores or ulcers without being noticed. In severe cases, an infection can spread to the bone or lead to tissue death. Removal (amputation) of a toe, foot or even part of the leg may be necessary.
- Urinary tract infections and urinary incontinence. If the nerves that control the bladder are damaged, the bladder may not empty completely when urinating. Bacteria can build up in the bladder and kidneys, causing urinary tract infections. Nerve damage can also affect the ability to feel the 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 the body's ability to adjust blood pressure. This can cause a sharp drop in pressure when standing after sitting or lying down, which may lead to lightheadedness and fainting.
- Digestive problems. If nerve damage occurs in the digestive tract, constipation or diarrhea, or both are possible. Diabetes-related nerve damage can lead to gastroparesis, a condition in which the stomach empties too slowly or not at all. This can cause 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 the sweat glands work and make it difficult for the body to control its temperature properly.
You can prevent or delay diabetic neuropathy and its complications by closely managing your blood sugar and taking good care of your feet.
Blood sugar management
The ADA recommends that people living with diabetes have a glycated hemoglobin (A1C) test at least twice a year. This test indicates your average blood sugar level for the past 2 to 3 months.
A1C goals may need to be individualized, but for many adults, the ADA recommends an A1C of less than 7.0%. If your blood sugar levels are higher than your goal, you may need changes in your daily management, such as adding or adjusting your medications or changing your diet or physical activity.
Foot problems, including sores that don't heal, ulcers and even amputation, are common complications of diabetic neuropathy. But you can prevent many of these problems by having a thorough foot exam at least once a year. Also have your health care provider check your feet at each office visit and take good care of your feet at home.
Follow your health care provider's recommendations for good foot care. To protect the health of your feet:
- Check your feet every day. Look for blisters, cuts, bruises, cracked and peeling skin, redness, and swelling. Use a mirror or ask a friend or family member to help examine parts of your feet that are hard to see.
- Keep your feet clean and dry. Wash your feet every day with lukewarm water and mild soap. Don't soak your feet. Dry your feet and between your toes thoroughly.
- Moisturize your feet. This helps prevent cracking. But don't get lotion between your toes because it might encourage fungal growth.
- Trim your toenails carefully. Cut your toenails straight across. File the edges carefully so that you have smooth edges. If you can't do this yourself, a specialist in foot problems (podiatrist) can help.
- Wear clean, dry socks. Look for socks made of cotton or moisture-wicking fibers that don't have tight bands or thick seams.
- Wear cushioned shoes that fit well. Wear closed-toed shoes or slippers to protect your feet. Make sure your shoes fit properly and allow your toes to move. A foot specialist can teach you how to buy properly fitted shoes and to prevent problems such as corns and calluses. If you qualify for Medicare, your plan may cover the cost of at least one pair of shoes each year.