Encyclopedia of Health and Medicine

D
dehydroepiandrosterone (DHEA) A precursor
steroid HORMONE the adrenal cortex of the ADRENAL
GLANDS synthesizes from cholesterol. The OVARIES
or TESTES, and to a lesser extent the adrenal cortex,
further formulate DHEA into TESTOSTERONE and
ESTROGENS. LUTEINIZING HORMONE (LH) provides the
hormonal stimulus for this synthesis. Levels of
DHEA in the BLOOD circulation begin to rise
around age 10, preceding the onset of PUBERTY,
and peak in the mid-20s. DHEA levels in the
bloodstream decline by about 15 percent a decade
until about age 75, at which point the level stabilizes
at about 15 percent of what it was at its peak
50 years earlier. Though there is speculation that
diminishing DHEA levels may in some way precipitate
the changes that take place with aging,
researchers have yet to identify the mechanisms
responsible.
See also ANABOLIC STEROIDS AND STEROID PRECUR-
SORS; DHEA SUPPLEMENT.
diabetes A condition, clinically known as diabetes
mellitus, in which the ISLETS OF LANGERHANS
do not produce enough INSULIN or the body’s cells
do not appropriately respond to insulin, resulting
in an inability of the cells to accept GLUCOSE. There
are three major forms of diabetes: type 1, type 2,
and gestational. Lifestyle factors significantly
influence the development and course of diabetes,
particularly type 2. Diabetes is the most common
endocrine disorder.
Diabetes is a significant health concern in the
United States, with more than 13 million people
knowing they have the condition. Another 5 or 6
million have diabetes though are unaware. Diabetes
is the sixth leading cause of death in the
United States, directly claiming 70,000 lives each
year. As a leading cause of CARDIOVASCULAR DISEASE
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(CVD), kidney disease, and RENAL FAILURE, diabetes
contributes to thousands more deaths as well. Diabetes
is also the primary cause of VISION IMPAIRMENT
and blindness, and a significant cause of peripheral
NEUROPATHY (NERVE damage), among American
adults.
Medical texts that are several thousand years
old make reference to diabetes. Ancient physicians
identified diabetes as the “honey URINE” disease, a
moniker that became refined through the centuries
to the somewhat less graphic “sugar diabetes.”
Until the discovery of insulin in the early
1920s, the diagnosis of diabetes was a death sentence.
Efforts to manage the disease by restricting
sugar were futile because the true problem was
not too much sugar but rather not enough insulin.
As researchers and doctors gained greater
understanding of diabetes, they realized it was
insulin that made possible glucose’s entry into the
cells. Doctors now know diabetes results from the
body’s inability to produce or use insulin, which
allows glucose (sugar) to accumulate in the BLOOD
and spill over into the urine. Insulin therapy
became the breakthrough in treatment that
restored the potential for relatively normal lives
for those who developed diabetes.
Type 1 Diabetes
Type 1 diabetes is an autoimmune disorder in
which the IMMUNE SYSTEM produces antibodies that
attack and destroy the cells of the islets of Langerhans.
As a result, the body cannot produce
insulin. An interplay between genetic and environmental
factors is likely, with some researchers
suspecting the autoimmune reaction follows INFEC-
TION with a VIRUS. People who have type 1 diabetes
must take regular insulin injections to meet their
insulin needs and check their blood glucose levels