Definition and Overview

Patients with uncontrolled type 1 or type 2 diabetes are at risk of various complications because of their high blood sugar levels. One of these complications is neuropathy, a medical condition characterised by damage to nerves in different parts of the body, causing them to lose their ability to transmit nerve impulses in a normal way. Up to 70% of diabetic patients develop some form of neuropathy, which severity ranges from very mild (asymptomatic) to severe (symptoms can be disabling and even fatal). Although the condition can affect all organ systems, including the urinary tract, digestive system, and the heart, the most commonly affected are the nerves in the lower extremities.

There are four types of diabetic neuropathy classified based on the location of the affected nerves. These are:

  • Peripheral diabetic neuropathy - The most common form of diabetic neuropathy that affects the nerves in the arms, hands, legs, and feet. It can result in foot deformities, infections, and ulcers, which in most severe cases lead to amputations.

  • Proximal neuropathy - The form of neuropathy characterised by decreased sensation, nerve damage, and/or pain in the legs, thighs, buttocks, and hips.

  • Autonomic neuropathy - The form of diabetic neuropathy that damages the nerves in the heart and circulatory system, affecting various bodily functions, including temperature regulation, blood pressure, urination, and sexual response.

  • Focal neuropathy - Also commonly referred to as mononeuropathy, it affects a single nerve often in the foot, thigh, or wrist. It may also affect the nerves in the chest, back, and those that control the muscles in the eyes.

Causes of Condition

The exact mechanism by which diabetes causes neuropathy is not fully understood. However, it has been observed that the risk of nerve fibers from weakening is highest in people who:

  • Have problems keeping their blood sugar level under control

  • Are obese

  • Have high blood pressure and kidney disease

  • Are smoking

  • Have been suffering from diabetes for at least 25 years

Key Symptoms

The signs and symptoms of the condition vary depending on the type of neuropathy the patient has, its severity, and the specific nerves affected.

Peripheral neuropathy

  • Electric-shock sensations

  • Foot pain, infections, ulcers, or deformities

  • Loss of coordination, balance, and reflexes

  • Muscle weakness, cramping, or twitching

  • Numbness

  • Reduced ability to feel temperature changes and pain

  • Sharp cramps

  • Tingling

  • Symptoms get worse at night

Proximal neuropathy

  • Pain or weakness in arms

  • Sudden, severe pain in the upper thigh, hip, and buttocks (often only on one side of the body)

  • Trouble standing up from a seated position

  • Weakness in the legs

Autonomic neuropathy

  • Bladder problems

  • Difficulty swallowing

  • Digestion problems

  • Erectile dysfunction in men

  • Eye problems

  • Gastroparesis

  • Hypoglycemia unawareness

  • Inability to adjust blood pressure and heart rate

  • Increased heart rate when at rest

  • Increased or decreased sweating

  • Persistent nausea, vomiting, bloating, and loss of appetite

  • Uncontrolled diarrhea

  • Vaginal dryness in women

  • Weight loss

Focal neuropathy

  • Bell’s Palsy

  • Chest or abdominal pain

  • Double vision

  • Eye pain

  • Inability to focus the eye

  • Pelvic or lower back pain

Who to See and Types of Treatments Available

The long-term management of diabetes involves regularly checking patients for signs of neuropathy, which often involves the following:

  • Review of the patient’s medical history and symptoms

  • Physical exam - Checking the patient’s blood pressure, heart rate, muscle strength, reflexes, and ability to move

  • Blood tests - Used to rule out other possible causes of symptoms, including thyroid problems, certain infections, and vitamin B12 deficiency, among others

  • Foot exam - A comprehensive foot exam is recommended for patients diagnosed with type 1 or type 2 diabetes. It involves checking the patient’s legs and foot for any signs of nerve damage, including swelling, ulcers that are slow to heal, and deformities. The protective sensation or feeling in the feet is also assessed through a non-invasive procedure called monofilament test. This involves touching specific areas of the foot using a soft nylon fiber. People who are unable to sense pressure from the monofilament have lost protective sensation.

  • Nerve conduction studies - Used to determine nerve damage and its severity by measuring the conduction speed of an electrical impulse through a nerve. It is a very simple, non-invasive test that involves placing electrodes on the skin over the nerve being tested. This test is often followed by electromyography (EMG), which measures the electrical activity in muscles. The results of both tests help doctors located and assess nerve damage.

Treatment

Patients with diabetes are treated by an endocrinologist, a doctor with special training in the treatment and management of diseases of the endocrine system, which include diabetes. There is no known cure for diabetic neuropathy; its treatment focuses on relieving patient’s pain, restoring function, and ensuring that the condition does not progress. This often involves:

  • Keeping diabetes under control - Keeping blood glucose levels as close to normal as possible is the only way for patients to prevent or slow down the progression of any complications associated with diabetes. An endocrinologist helps patients determine their target blood glucose levels, which depends on their age, overall health condition, how long they had diabetes, and if they have other existing medical conditions. To achieve normal blood glucose levels, patients are often prescribed with insulin and advised to make lifestyle changes including eating a healthy, well-balanced diet and being more active.

  • Pain-relief - Nerve pain can be treated with medications, acupuncture, and physical therapy. Common drugs that are prescribed to relieve nerve pain associated with diabetes are anti-seizure medications and antidepressants. It is important to note that such medications are associated with complications, which doctors must fully explain to patients. Normally, these drugs are only prescribed if their expected benefits outweigh their possible risks or side effects.

  • Medications - Other types of drugs are also often prescribed to manage other complications and restore function. For example, urinary tract problems are often treated with antispasmodic medications while sexual dysfunction may be managed with medications designed to improve blood flow to the penis, such as Viagra.

References:

  • Diabetic neuropathies: The nerve damage of diabetes. National Institute of Diabetes and Digestive and Kidney Diseases. http://diabetes.niddk.nih.gov/dm/pubs/neuropathies/index.aspx.

  • Amato AA, et al. Peripheral neuropathy. In: Harrison’s Principles of Internal Medicine. 18th ed. New York, N.Y.: The McGraw-Hill Companies; 2012. http://www.accessmedicine.com.

  • Bril, V., England, J., Franklin, G. M., Backonja, M., Cohen, J., Del Toro, D., … & Zochodne, D. (2011, April 11). Evidence-based guideline: Treatment of painful diabetic neuropathy. Neurology, 76(20), 1758-1765. http://www.neurology.org/content/76/20/1758.full

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