What is Diabetic Neuropathies?

The term neuropathy indicates nerve disease or damage. When nerve damage is caused as a result of diabetes, it is called diabetic neuropathy. Diabetic neuropathy is not an individual disease, but a family of nerve disorders caused by diabetes.

Nerve damage occurs commonly in people with diabetes; about 60 to 70 percent of diabetics develop some form of neuropathy. Diabetes can affect any nerve at any time, but the risk of nerve damage increases with age and the duration of diabetes (more common in people who have had diabetes since a long time). Diabetic neuropathies are more common among people who have had diabetes for at least 25 years. Apart from these risk factors there are others such as high blood sugar levels (poorly controlled diabetes), high levels of blood fat, blood pressure and being overweight or obese.

Diabetes over time, can damage nerves throughout your body. In the initial stages, nerve damage may not cause any symptoms. Some people with nerve damage may be asymptomatic (have no symptom) whereas others may have pain, tingling, or numbness or loss of feeling in the hands, arms, feet and legs.  Diabetic neuropathy can involve nerve of every organ system, including the digestive tract, heart and sex organs.

What causes diabetic neuropathy?

Nerve is damaged in people with diabetes due to high blood sugar levels. Increased blood sugar levels for a prolonged period can damage nerves throughout the body. The risk of nerve damage is higher in people with poorly controlled blood sugar levels (higher blood sugar levels for a prolonged period); this makes controlling blood sugar in the target range, important.

Types of diabetic neuropathy

The three kinds of diabetic neuropathy include peripheral neuropathy, autonomic neuropathy and focal neuropathy. Diabetes can affect any nerve at any time throughout the body (table 1).

Peripheral neuropathy: When the peripheral nerves in the body are damaged, it is known as peripheral neuropathy. Peripheral nerves are nerves that affect movement, muscle strength and sensation (such as pain, touch, hot and cold). Peripheral neuropathy mostly affects the nerves in the feet and lower legs. Involvement of the nerves in the legs can lead to serious foot problems. In most cases, the nerve damage worsens slowly over a period of months or years.

Autonomic neuropathy: When the autonomic nerves in the body are damaged, it is referred to as autonomic neuropathy. Autonomic nerves are nerves that affect functions such as heartbeat, blood pressure, sweating, digestion, urination and sexual function.

Focal neuropathy: When the disease involves just one nerve such as nerve in the wrist, thigh or foot, it is referred to as focal neuropathy. In most cases, focal neuropathy occurs suddenly.

Treatment of diabetic neuropathy involves the control of blood glucose levels by bringing it down to as normal as possible and using medications such as pain relievers and others as needed depending on the type of nerve damage.

Diagnosis of Diabetic Neuropathies

Diabetic neuropathies are diagnosed by health care professionals based on symptoms and a physical exam. During a physical exam, the doctor will check your blood pressure, heart rate and perform a detailed neurological examination. In the neurological examination, functions such as muscle strength, reflexes and sensitivity to position changes, vibration, temperature, or light touch are checked. If needed some special tests may be done to determine the cause of your symptoms and suggest treatment.

Foot Exams: According to experts, anyone with diabetes should get a foot exam done each year by a doctor or by a foot specialist (podiatrist) to check for peripheral neuropathy. If you are diagnosed with peripheral neuropathy, frequent foot exams will be recommended. During the foot exam, the skin, muscles, bones, circulation and sensation of the feet are checked; your doctor may do a filament test. In this test, protective sensation or feeling in your feet is checked by touching the foot with a nylon monofilament present on a wand or by pricking the foot with a pin. If you cannot feel the pinprick or touch of the monofilament, it suggests that you have lost the protective sensation. This increases your risk of developing foot sores that may not heal properly. Your ability to feel temperature and vibration may also be assessed.

Nerve conduction studies or electromyography: This test is done to determine the type and extent of nerve damage. In this study, the transmission of electrical current through a nerve is assessed. When the test is being done, an image of the nerve impulse is formed on a screen as it transmits an electrical signal. If impulses seem slower or weaker than usual, it is suggestive of damage to the nerve. Your doctor can assess the condition of all the nerves in the arms and legs with this test. Electromyography checks the response of muscle to electrical signals transmitted by nearby nerves. The test is usually performed along with nerve conduction studies. In most people, these tests are not done to diagnose neuropathy.

Autonomic testing: The test assesses the function of autonomic nerves. Heart rate variability (change in heart rate) due to deep breathing, changes in blood pressure and posture may be checked to assess the function of autonomic nerves.

Ultrasound: This painless and non-invasive test uses high-frequency sound waves (which cannot be heard by human ears) to evaluate structures inside the body. The pattern of the echoes produced when the sound waves are reflected from the internal structure creates a picture called a sonogram. The radiologist can differentiate healthy tissues and abnormal pattern on this picture. Ultrasound of the bladder and other parts of the urinary tract can show if the bladder empties completely after urination or not.

Nerve biopsy: If needed, the doctor may take a sample of the nerve tissue for examination. This test is mostly done in research settings.

These are some tests that are done if your doctor suspects autonomic neuropathy. Apart from this, your doctor may refer you to a physician, who specializes in digestive disorders (gastroenterologist) for additional tests.

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