The Nerve Damage of Diabetes
What Causes Diabetic Neuropathy?
Scientists do not know what causes diabetic
neuropathy, but several factors are likely to contribute to the disorder. High
blood glucose, a condition associated with diabetes, causes chemical changes in
nerves. These changes impair the nerves' ability to transmit signals. High
blood glucose also damages blood vessels that carry oxygen and nutrients to the
nerves. In addition, inherited factors probably unrelated to diabetes may make
some people more susceptible to nerve disease than others.
How high blood glucose leads to nerve damage
is a subject of intense research. The precise mechanism is not known.
Researchers have discovered that high glucose levels affect many metabolic
pathways in the nerves, leading to an accumulation of a sugar called sorbitol
and depletion of a substance called myoinositol. However, studies in humans
have not shown convincingly that these changes are the mechanism that causes
More recently, researchers have focused on
the effects of excessive glucose metabolism on the amount of nitric oxide in
nerves. Nitric oxide dilates blood vessels. In a person with diabetes, low
levels of nitric oxide may lead to constriction of blood vessels supplying the
nerve, contributing to nerve damage. Another promising area of research centers
on the effect of high glucose attaching to proteins, altering the structure and
function of the proteins and affecting vascular function.
Scientists are studying how these changes
occur, how they are connected, how they cause nerve damage, and how to prevent
and treat damage.
What Are the Symptoms of Diabetic Neuropathy?
The symptoms of diabetic neuropathy vary. Numbness and tingling in feet are
often the first sign. Some people notice no symptoms, while others are severely
disabled. Neuropathy may cause both pain and insensitivity to pain in the same
person. Often, symptoms are slight at first, and since most nerve damage occurs
over a period of years, mild cases may go unnoticed for a long time. In some
people, mainly those afflicted by focal neuropathy, the onset of pain may be
sudden and severe.
What Are the Major Types of Neuropathy?
The symptoms of neuropathy also depend on which nerves and what part of the
body is affected. Neuropathy may be diffuse, affecting many parts of the body,
or focal, affecting a single, specific nerve and part of the body.