Diabetic Neuropathy Basics: Types, Symptoms and Evaluation

Numb toes, burning feet at night, a stomach that empties slowly, dizziness on standing. These can all be forms of diabetic neuropathy, which is nerve damage linked to diabetes. This page describes what it is, the four types that authorities distinguish, how it is usually evaluated, and what is said about foot care and glucose control. It is educational. It does not diagnose, and it makes no treatment recommendations. For the wider picture of the condition behind it, see diabetes and metabolic health.

What diabetic neuropathy is

Nerves carry signals between the brain, the spinal cord and the rest of the body. Over time, high blood glucose can damage them. The US National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) describes diabetic neuropathy as one condition with several forms, with symptoms that range from pain and numbness in the feet to problems with internal organs such as the heart and bladder.

It is common. The NIDDK says about one-third to one-half of people with diabetes have peripheral neuropathy, one of the forms. The National Institute of Neurological Disorders and Stroke (NINDS) states that diabetes is the leading cause of peripheral neuropathy in the United States and that about two thirds of people with diabetes have mild to severe nerve problems. The figures differ, and the pages do not say why, but both bodies describe the condition as frequent.

The four main types

Peripheral neuropathy usually affects the feet and legs and sometimes the hands and arms. Mayo Clinic, which calls it peripheral sensorimotor neuropathy, lists loss of feeling or reduced ability to sense pain or temperature, a tingling or burning feeling, sharp pains or cramps, muscle weakness, and heightened sensitivity to touch. In some people even the weight of a bedsheet is painful. Serious foot problems such as ulcers, infections and bone and joint damage can follow.

Autonomic neuropathy affects the nerves that run internal organs. The NIDDK says this can involve heart rate and blood pressure, digestion, the bladder, sex organs, sweat glands and the eyes. Mayo Clinic lists dizziness on standing, a fast resting heartbeat, bladder or bowel problems, slow stomach emptying (gastroparesis) and altered sweating. It can also dull the usual warning signs of low blood sugar, called hypoglycemia unawareness.

Proximal neuropathy, also called diabetic polyradiculopathy, is rare but disabling. It affects the hip, buttock or thigh, usually on one side. Mayo Clinic lists serious pain in the buttock, hip or thigh, weak and shrinking thigh muscles, and trouble rising from a seat. The NIDDK says symptoms tend to improve gradually over months or years.

Focal neuropathy, also called mononeuropathy, involves a single nerve, most often in the hand, head, torso or leg. The NIDDK identifies entrapment syndromes such as carpal tunnel syndrome as the most common kind. Mayo Clinic adds examples including double vision, one-sided facial weakness, hand numbness and foot drop (trouble lifting the front of the foot).

A person can have more than one type. Symptoms depend on which nerves are affected.

Symptoms worth raising with a clinician

Mayo Clinic lists these as times to see a doctor: a foot cut or sore that is infected or will not heal, burning, tingling, weakness or pain in the hands or feet that interferes with daily activities or sleep, changes in digestion, urination or sexual function, and dizziness and fainting. Thyroid disease, for instance, can produce overlapping nerve symptoms; see thyroid problems and nerve symptoms.

How it is diagnosed in general

There is no single test. According to Mayo Clinic, a healthcare professional starts with a physical exam and questions about symptoms and medical history, and most often checks muscle strength and tone, reflexes, and sensitivity to touch, pain, temperature and vibration. Further tests that may be done or ordered include:

• Filament testing, in which a soft nylon fibre called a monofilament is brushed over the skin to check touch sensitivity.
• Sensory testing of how nerves respond to vibration and temperature change.
• Nerve conduction studies, which measure how quickly nerves in the arms and legs conduct electrical signals.
• Electromyography (EMG), often called needle testing, which measures electrical activity in muscles and is often done along with nerve conduction studies.
• Autonomic testing, which looks at how blood pressure and heartbeat change with position and whether sweating is within the standard range.

The NINDS adds that blood tests can detect diabetes, vitamin deficiencies, liver or kidney dysfunction and other metabolic disorders, which helps rule other causes in or out. This matters because someone with diabetes can still have nerve symptoms from another cause.

Who may be involved

Care is often shared. Mayo Clinic says that people with symptoms of neuropathy may be referred to a neurologist, a doctor who specialises in the brain and nervous system, and that people with diabetes complications are often referred to an endocrinologist if they do not already see one. A neurologist is also the specialist who typically performs and interprets EMG and nerve conduction studies, according to Mayo Clinic's EMG page. Mayo Clinic mentions a urologist for urinary tract problems and a cardiologist for heart-related conditions, and the NIDDK notes that a podiatrist may be on the team.

Referral practice varies between health systems and countries, and not every person needs a neurologist. Who is involved depends on the symptoms and on how care is organised locally.

Why foot care and glucose control are emphasised

The two themes recur across sources for practical reasons. Feet are where peripheral neuropathy often starts and where its consequences can be the most serious. The NIDDK explains that when you lose feeling in your feet, you may not notice a pebble in your sock or a blister, which can lead to cuts and sores, and cuts and sores can become infected. It states that daily foot checks help spot problems early, and that people can lower their chances of diabetes-related foot problems by taking care of their feet every day. Its diabetes and foot problems page is the place to read the specifics of that care.

Glucose control is emphasised because it is the main lever for slowing the condition. Mayo Clinic states that the key way to prevent or delay nerve damage is to keep blood sugar within the target range, and that good control may even improve some current symptoms. It stresses that target ranges are tailored for each person, based on factors such as age, how long someone has had diabetes, and overall health. Mayo also lists blood pressure control, a healthy weight, physical activity and not smoking among helpful measures. For bone-related effects of diabetes, see osteoporosis and bone health, and for fall risks at home see fall prevention at home.

What is said about treatment

Mayo Clinic states that diabetic neuropathy has no known cure, and describes treatment goals as slowing the disease, relieving pain, managing related health issues and helping affected body parts work better. For pain, it notes that many prescription medicines exist, including certain anti-seizure medicines and certain antidepressants, that they do not work for everyone, and that a clinician should discuss benefits and side effects. It says to check with a healthcare professional before using any supplement or alternative treatment. This page does not recommend any particular treatment, and decisions belong to the person and the treating team.

Honest limits

No source promises that existing nerve damage will reverse, and Mayo Clinic says plainly that there is no known cure. Loss of feeling can hide problems, as the NIDDK's pebble-in-the-sock example shows. Estimates of how common neuropathy is vary by source, and this page cannot say how screening and targets are set in your country or clinic. Individual care varies, and your own doctor or specialist has the final word. For help preparing for a visit, see questions to ask an endocrinologist.

The short version

Diabetic neuropathy covers four main patterns, peripheral, autonomic, proximal and focal, and it is common among people with diabetes. Evaluation relies on an examination and simple sensory tests, with nerve conduction studies and EMG used in some cases and a neurologist involved when needed. Major health bodies stress glucose control and daily foot care because they are the main ways to slow the condition and prevent its worst consequences.