The Nerve Damage of Diabetes
What Is Diabetic Neuropathy?
Diabetic neuropathy is a nerve disorder caused by diabetes. Symptoms of
neuropathy include numbness and sometimes pain in the hands, feet, or legs.
Nerve damage caused by diabetes can also lead to problems with internal organs
such as the digestive tract, heart, and sexual organs, causing indigestion,
diarrhea or constipation, dizziness, bladder infections, and impotence. In some
cases, neuropathy can flare up suddenly, causing weakness and weight loss.
Depression may follow. While some treatments are available, a great deal of
research is still needed to understand how diabetes affects the nerves and to
find more effective treatments for this complication.
DCCT: Can Diabetic Neuropathy Be Prevented?
A 10-year clinical study that involved 1,441 volunteers with
insulin-dependent diabetes (IDDM) was recently completed by the National
Institute of Diabetes and Digestive and Kidney Diseases. The study proved that
keeping blood sugar levels as close to the normal range as possible slows the
onset and progression of nerve disease caused by diabetes. The Diabetes Control
and Complications Trial (DCCT) studied two groups of volunteers: those who
followed a standard diabetes management routine and those who intensively
managed their diabetes. Persons in the intensive management group took multiple
injections of insulin daily or used an insulin pump and monitored their blood
glucose at least four times a day to try to lower their blood glucose levels to
the normal range. After 5 years, tests of neurological function showed that the
risk of nerve damage was reduced by 60 percent in the intensively managed
group. People in the standard treatment group, whose average blood glucose
levels were higher, had higher rates of neuropathy. Although the DCCT included
only patients with IDDM, researchers believe that people with
noninsulin-dependent diabetes would also benefit from maintaining lower levels
of blood glucose.
How Common Is Diabetic Neuropathy?
People with diabetes can develop nerve
problems at any time. Significant clinical neuropathy can develop within the
first 10 years after diagnosis of diabetes and the risk of developing
neuropathy increases the longer a person has diabetes. Some recent studies have
- 60 percent of patients with diabetes have some form of
neuropathy, but in most cases (30 to 40 percent), there are no
- 30 to 40 percent of patients with diabetes have symptoms
suggesting neuropathy, compared with 10 percent of people without
- Diabetic neuropathy appears to be more common in smokers,
people over 40 years of age, and those who have had problems controlling their
blood glucose levels.
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.