Neuropathy (Nerve Damage)

Neuropathy means damage to the nerves and conditions that arise as a result of this damage and it is the most common complication of diabetes. It may affect a single nerve or groups of nerves and has numerous clinical manifestations. Symptoms may be few or absent, especially in the early stages, but some forms of neuropathy cause severe pain and are highly disabling. The cause of diabetic neuropathy is not fully understood, but two, and possibly three, sets of factors are believed to be important. First, hyperglycaemia in diabetes causes increased activation of a biochemical pathway known as the polyol pathway.

There is an accumulation of sorbitol and fructose (sugars derived from glucose) within nerves, which interferes with other biochemical reactions and impairs the ability to transmit electrical signals. Secondly, again as a result of hyperglycaemia, the disruption of biochemical pathways is believed to cause damage to blood vessels supplying nerves, possibly starving them of oxygen and nutrients and contributing to the damage seen in neuropathy. Thirdly, other conditions, not directly connected with diabetes, may contribute to the development of neuropathy in some people. Studies have shown that good, and especially 'tight', glycaemic control can greatly reduce the incidence and progression of clinical (i.e. detectable) neuropathy in diabetes.

Sensory nerves carry signals from the sense organs to the brain and are involved in the perception of the senses such as touch and pain. Motor nerves carry signals from the brain and spinal cord to voluntary muscles that move limbs and joints. The autonomic nervous system governs all the unconscious, involuntary functions of the body such as control of the major organs, such as the heart, kidneys, gastrointestinal system, bladder and so on. Neuropathy can affect one or more nerves involved in all these areas of the nervous system and this helps to explain why the manifestations can be so diverse. Several stages in the development and progression of neuropathy are recognized.

• Biochemical changes within nerves, as in the abnormal build up of sorbitol. Produces no symptoms.
• Reduced ability of nerves to conduct electrical impulses so that speed of conduction is reduced. Maybe detected by electrophysiological measurements but causes no symptoms.
• Clinical neuropathy, which can be diagnosed using vari ous tests, depending upon the type
• Late or end-stage complications in which there is sig nificant damage to nerves and disruption of their func tion, with surrounding tissues affected. Examples include ulcers,gangrene and Charcot's foot or charcot neuro arthropathy.

See more diabetic complications information.