Diabetic Neuropathy

Page 1 2 3

What is Diabetic Neuropathy?

This animation brought to you by Blausen Medical Communications.
Contact Andrew Walbank.

Diabetic neuropathy is a type of nerve damage that happens in people who have diabetes. It affects mainly the peripheral nerves.

There are three types of peripheral nerve affected: motor, sensory, and autonomic. Motor nerve fibres carry signals to muscles to allow motions like walking and fine finger movements. Sensory nerves take messages in the opposite direction. They carry information to the brain about shape, movement, texture, warmth, coolness, or pain from special sensors in the skin and from deep in the body. Autonomic nerves are nerves that are not consciously controlled. These nerves have functions such as controlling the heart rate, maintaining blood pressure, and controlling sweating.

Damage to these nerves makes it hard for the nerves to carry messages to the brain and other parts of the body. This can result in numbness (loss of feeling) or painful tingling in parts of the body.

Diabetic neuropathy can also affect the following:

Strength and feeling in different body parts.
Ability of the heart to keep up with the body's needs.
Ability of the intestines to digest food.
Ability to achieve an erection (in men).

Who gets Diabetic Neuropathy?

Diabetes mellitus is a common medical condition in the Australian community. It is estimated that approximately one in four Australians over the age of 25 years has diabetes or its precursor, impaired glucose metabolism (also associated with increased risk of heart disease). People with diabetes can develop nerve problems at any time, but the longer a person has diabetes, the greater the risk. Patients with type 2 diabetes are at greater risk particularly if they have poor control of their blood sugars. The highest rates of neuropathy are among people who have had the disease for at least 25 years.

An estimated 10 to 65% of those with diabetes have some form of neuropathy, but not all with neuropathy have symptoms. Painful diabetic neuropathy affects approximately one quarter of patients with diabetes. Diabetic neuropathy also appears to be more common in people who have had problems controlling their blood glucose levels, in those with high levels of cholesterol and high blood pressure, in overweight people, and in people over the age of 40.

The most common type is peripheral neuropathy, also called distal symmetric neuropathy, which affects the arms and legs. This is experienced by approximately 50% of diabetic patients suffering from neuropathy. Diabetic neuropathy also appears to be more common in males than in females.

Predisposing Factors

Diabetes can damage peripheral nervous tissue in a number of ways. There are many theories that have been suggested, and it is generally accepted that there are multiple causes of diabetic neuropathy. These causes are probably different for the different types of diabetic neuropathy.

Overall, the most significant risk factor for the development and progression of diabetic neuropathy is glycaemic control. Glycaemic control refers to how well a patient's blood sugar level is kept within normal (physiological) limits.

Other risk factors for the development of diabetic neuropathy include:

Increasing age.
Genetic risk.
Cigarette smoking.
Alcohol use.
High blood pressure.
Hypercholesterolaemia (high blood cholesterol).

Note that many of these risk factors are potentially modifiable. Controlling the above risk factors will therefore prevent disease.

Progression

Peripheral neuropathy (distal symmetric polyneuropathy)

Peripheral neuropathy affects the nerves in the arms, hands, legs, and feet. The feet and legs are likely to be affected before the hands and arms. You may notice signs such as pain, weakness, reduced sensation or altered sensations (such as increased sensitivity to pain or touch). The classic description of diabetic neuropathy is called a 'glove and stocking anaesthesia.' This refers to altered sensation that first develops in the extremities and slowly progresses to involve more proximal areas. Many people with diabetes have signs of neuropathy upon examination but have no symptoms at all.

Poor sensation in the feet can lead to complications such as severe ulcers, infections and in extreme circumstances the need for amputation. Peripheral neuropathy may also cause muscle weakness and loss of reflexes, especially at the ankle, leading to changes in gait (walking). Foot deformities, such as hammertoes and the collapse of the midfoot, may occur. Blisters and sores (ulcers) may appear on numb areas of the foot because pressure or injury goes unnoticed.

If foot injuries are not treated promptly, the infection may spread to the bone, and the foot may then have to be amputated. Some experts estimate that half of all such amputations are preventable if minor problems are caught and treated in time.

Autonomic neuropathy

Autonomic neuropathy affects the nerves in the lungs, heart, stomach, intestines, bladder, and sex organs.

Autonomic neuropathy affects the nerves that control the heart, regulate blood pressure, and control blood glucose levels. It also affects other internal organs, causing problems with digestion, respiratory function, urination, sexual response, and vision.

In addition, the system that restores blood glucose levels to normal after a hypoglycaemic (low blood sugar) episode may be affected, resulting in loss of the warning signs of hypoglycaemia such as sweating and palpitations.

This type of neuropathy is rare.

Proximal neuropathy

Proximal neuropathy, sometimes called lumbosacral plexus neuropathy, femoral neuropathy, or diabetic amyotrophy, starts with pain in either the thighs, hips, buttocks, or legs, usually on one side of the body.

This type of neuropathy is more common in those with type 2 diabetes and in older people. It causes weakness in the legs, manifested by an inability to go from a sitting to a standing position without help. Treatment for weakness or pain is usually needed. The length of the recovery period varies, depending on the type of nerve damage.

Focal neuropathy

Occasionally, diabetic neuropathy appears suddenly and affects specific nerves, most often in the head, torso, or leg. Focal neuropathy is painful and unpredictable and occurs most often in older people. However, it tends to improve by itself over weeks or months and does not cause long-term damage.

People with diabetes also tend to develop nerve compressions, also called entrapment syndromes. One of the most common is carpal tunnel syndrome, which causes numbness and tingling of the hand and sometimes muscle weakness or pain. Other nerves susceptible to entrapment may cause pain on the outside of the shin or the inside of the foot.

Page 1 2 3