Causes
Diabetic neuropathy is a complication of diabetes, primarily caused by prolonged exposure to high blood sugar levels. Other factors that contribute to nerve damage include: High blood glucose (hyperglycemia): This is the leading cause. High glucose levels can damage blood vessels that supply nerves with oxygen and nutrients, and can also directly injure nerve fibers. Inflammation: Chronic inflammation associated with diabetes can contribute to nerve damage. Genetic factors: Some people may be genetically more susceptible to nerve damage from diabetes.- Lifestyle factors:
- Smoking
- Excessive alcohol consumption
- Obesity
- Duration of diabetes: The longer a person has diabetes, especially if blood sugar is poorly controlled, the higher the risk of developing neuropathy.
Symptoms
Symptoms of diabetic neuropathy vary depending on which nerves are affected. The four main types of diabetic neuropathy are peripheral, autonomic, focal, and proximal.- Peripheral Neuropathy (most common, affecting feet and legs, then hands and arms):
- Numbness or reduced ability to feel pain or temperature changes
- Tingling or burning sensation
- Sharp pains or cramps
- Increased sensitivity to touch, even light touch
- Muscle weakness
- Loss of reflexes, especially in the ankle
- Loss of balance and coordination
- Foot problems (ulcers, infections, bone and joint damage)
- Autonomic Neuropathy (affecting nerves that control internal organs):
- Digestive system: Nausea, vomiting, bloating, early fullness, constipation, diarrhea (especially at night), difficulty swallowing.
- Urinary tract: Bladder control problems, difficulty emptying the bladder, increased risk of urinary tract infections.
- Sexual function: Erectile dysfunction in men, vaginal dryness or difficulty with arousal in women.
- Sweat glands: Decreased or increased sweating, especially at night.
- Cardiovascular system: Dizziness or faintness upon standing (orthostatic hypotension), rapid heart rate at rest.
- Eye: Difficulty adjusting from light to dark.
- Proximal Neuropathy (affecting nerves in thighs, hips, buttocks, or legs):
- Severe pain in one side of the body (thigh, hip, buttock).
- Weakness and muscle wasting in the thigh.
- Difficulty rising from a sitting position.
- Focal Neuropathy (affecting a single nerve, often in the head, torso, or leg):
- Sudden pain in a specific area (e.g., chest, stomach, leg, foot).
- Paralysis on one side of the face (Bell's palsy).
- Double vision or difficulty focusing.
Diagnosis
Diagnosing diabetic neuropathy involves a thorough medical history, physical examination, and various tests to assess nerve function.- Medical history and physical exam: The doctor will ask about your diabetes management, symptoms, and check your reflexes, sensation (to touch, temperature, vibration), and muscle strength.
- Nerve conduction studies (NCS): Measure how quickly electrical signals travel through your nerves.
- Electromyography (EMG): Measures the electrical activity of muscles in response to nerve stimulation.
- Quantitative sensory testing (QST): Evaluates your ability to feel vibration and temperature.
- Autonomic testing: Specific tests to assess heart rate variability, blood pressure response to position changes, and sweat production.
- Nerve biopsy: Rarely performed, but may be considered in complex cases to rule out other causes of neuropathy.
Treatment
The primary goal of treating diabetic neuropathy is to manage blood sugar levels to prevent further nerve damage. Other treatments focus on relieving symptoms and managing complications.- Blood Glucose Control:
- Maintaining blood sugar levels within the target range through diet, exercise, and medications (insulin or oral diabetes medications) is the most critical step.
- Pain Management:
- Medications:
- Antidepressants: Tricyclic antidepressants (e.g., amitriptyline) and serotonin-norepinephrine reuptake inhibitors (SNRIs) like duloxetine (Cymbalta) can help relieve nerve pain.
- Anti-seizure medications: Pregabalin (Lyrica) and gabapentin (Neurontin) are often prescribed for neuropathic pain.
- Topical treatments: Capsaicin cream or lidocaine patches can provide localized pain relief.
- Physical therapy: Can help improve muscle strength, balance, and reduce pain.
- Transcutaneous electrical nerve stimulation (TENS): May provide some pain relief for certain individuals.
- Medications:
- Management of Complications:
- Foot care: Daily foot checks, proper footwear, and regular podiatrist visits are essential to prevent and manage foot ulcers and infections.
- Digestive issues: Dietary changes, medications for nausea, vomiting, constipation or diarrhea.
- Urinary problems: Medications, bladder training, or other interventions.
- Sexual dysfunction: Medications or other therapies.
- Orthostatic hypotension: Lifestyle changes (e.g., slow position changes, increased fluid intake) and medications.
- Lifestyle changes:
- Quit smoking.
- Limit alcohol consumption.
- Maintain a healthy weight.
- Regular exercise (as advised by your doctor).
Living With Diabetic Neuropathy
Nerve fibers already lost do not grow back, but progression can be slowed, pain can be treated, and the most serious consequence, a foot wound that will not heal, can almost always be prevented.
Glucose control slows it; nothing else has been shown to
Keeping A1C at target is the only treatment that changes the course of the nerve damage, and the benefit is in preventing what has not happened yet; our A1C guide explains the target. Not every numb foot in a person with diabetes is diabetic: years of metformin lower B12 absorption, and vitamin B12 deficiency causes an identical but treatable peripheral neuropathy, so B12 and thyroid levels are checked, and calf pain on walking is assessed for peripheral arterial disease rather than assumed to be nerve pain.
Pain medication: what to expect
Duloxetine, pregabalin, and gabapentin are the first choices, and a realistic goal is pain reduced by about half rather than gone. Each is started low and raised over two to four weeks; gabapentin and pregabalin are dosed lower when chronic kidney disease is present. Opioids, including tramadol, are avoided for long-term nerve pain because they work poorly and dependence risk is high; our chronic pain without opioids article covers the alternatives.
The feet: a daily routine in a barefoot climate
Lost sensation means an injury is not felt, and a Florida life of sandals, hot sand, pool decks, and bare feet indoors multiplies the chances. Feet are inspected daily, including the soles with a mirror, shoes are shaken out before wearing, and nothing is walked on barefoot. Any blister, cut, or red warm area that has not improved within a day or two is seen promptly. Our diabetic foot care guide sets out the routine, and a yearly monofilament foot exam is standard.
When the autonomic nerves are involved
Dizziness on standing from orthostatic hypotension, nausea and erratic glucose readings from gastroparesis, erectile dysfunction, and reduced sweating are all neuropathy too, and each has its own treatment. Impaired sweating and blood pressure regulation make summer heat a real hazard; our diabetes in Florida heat guide covers the precautions.
What cannot wait
A red, hot, swollen foot, with or without a wound, needs same-day assessment: it may be a spreading infection or Charcot foot, in which the bones of a numb foot collapse, and both threaten the limb if walked on. Our neurologic team coordinates testing and podiatry referral. The NIDDK and MedlinePlus publish patient guidance on nerve damage in diabetes.
If you have numbness or burning in your feet and have not had a foot exam or a B12 level in the past year, schedule a visit.