D

dehydroepiandrosterone (DHEA) A precursor
steroid HORMONEthe adrenal cortex of the ADRENAL
GLANDSsynthesizes 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 stabi-
lizes 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 pre-
cipitate 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 dia-
betes mellitus, in which the ISLETS OFLANGERHANS
do not produce enough INSULINor 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. Dia-
betes 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

(CVD), kidney disease, and RENAL FAILURE, diabetes

contributes to thousands more deaths as well. Dia-

betes is also the primary cause of VISION IMPAIRMENT

and blindness, and a significant cause of periph-

eral NEUROPATHY(NERVEdamage), 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 cen-

turies to the somewhat less graphic “sugar dia-

betes.” Until the discovery of insulin in the early

1920s, the diagnosis of diabetes was a death sen-

tence. 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 SYSTEMproduces antibodies that

attack and destroy the cells of the islets of Langer-

hans. As a result, the body cannot produce

insulin. An interplay between genetic and envi-

ronmental factors is likely, with some researchers

suspecting the autoimmune reaction follows INFEC-

TIONwith a VIRUS. People who have type 1 diabetes

must take regular insulin injections to meet their

insulin needs and check their blood glucose levels

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