Hearing
Loss Is Common in People with Diabetes
Hearing
loss is about twice as common in adults with diabetes compared to those who do
not have the disease, according to a new study funded by the National Institutes
of Health (NIH).
"Hearing
loss may be an under-recognized complication of diabetes. As diabetes becomes
more common, the disease may become a more significant contributor to hearing
loss," said senior author Catherine Cowie, Ph.D., of the National Institute
of Diabetes and Digestive and Kidney Diseases (NIDDK), who suggested that people
with diabetes should consider having their hearing tested. "Our study found
a strong and consistent link between hearing impairment and diabetes using a
number of different outcomes."
The
researchers discovered the higher rate of hearing loss in those with diabetes
after analyzing the results of hearing tests given
to a nationally representative sample of adults in the
United States
. The test measured participants’ ability to hear low, middle, and high
frequency sounds in both ears. The link between diabetes and hearing loss was
evident across all frequencies, with a stronger association in the high
frequency range. Mild or greater hearing impairment of low- or mid-frequency
sounds in the worse ear was about 21 percent in 399 adults with diabetes
compared to about 9 percent in 4,741 adults without diabetes. For high frequency
sounds, mild or greater hearing impairment in the worse ear was 54 percent in
those with diabetes compared to 32 percent in those who did not have the
disease.
Adults
with pre-diabetes, whose blood glucose is higher than normal but not high enough
for a diabetes diagnosis, had a 30 percent higher rate of hearing loss compared
to those with normal blood sugar tested after an overnight fast.
The
study, published early online June 17, 2008, in the Annals
of Internal Medicine, was conducted by researchers from the
NIDDK, the National Institute on Deafness and Other Communication Disorders (NIDCD),
components of the NIH, and Social & Scientific Systems, Inc., which provides
support on public health topics to NIH and other government agencies.
The
researchers analyzed data from hearing tests administered from 1999 to 2004 to
participants in the National Health and Nutrition Examination Survey (NHANES)
conducted by the
National
Center
for Health Statistics, part of the Centers for Disease Control and Prevention (CDC).
Half of the 11,405 survey participants aged 20 to 69 were randomly assigned to
have their hearing tested, and nearly 90 percent of them completed the hearing
exam and the diabetes questionnaire. The hearing test, called pure tone
audiometry, measures hearing sensitivity across a range of sound frequencies.
"Using
the data from the hearing tests, we measured hearing impairment in eight
different ways. Also, participants responded to questions about hearing loss in
the questionnaire, which asked whether they had a little trouble hearing, a lot
of trouble hearing, or were deaf without a hearing aid," said Cowie. In
addition, 2,259 of the participants who received hearing tests were randomly
assigned to have their blood glucose tested after an overnight fast.
Earlier
U.S.
studies that examined diabetes and hearing loss found a weaker association or
no association, but these studies were based on smaller samples of older adults,
and they were not nationally representative, according to co-author Howard
Hoffman, an epidemiologist at NIDCD. "This is the first study of a
nationally representative sample of working age adults, 20 to 69 years old, and
we found an association between diabetes and hearing impairment evident as early
as ages 30 to 40."
"The
link between diabetes and hearing loss has been debated since the 1960s or
before, and our results show that a relationship exists even when we account for
the major factors known to affect hearing, such as age, race, ethnicity, income
level, noise exposure, and the use of certain medications," noted Kathleen
Bainbridge, Ph.D., of Social & Scientific Systems, Inc.
Diabetes
may lead to hearing loss by damaging the nerves and blood vessels of the inner
ear, the researchers suggest. Autopsy studies of diabetes patients have shown
evidence of such damage.
Diabetes
is a group of diseases marked by high levels of blood glucose resulting from
defects in insulin production, insulin action, or both. Afflicting nearly 21
million people in the
United States
, it is a major cause of heart disease and stroke and the most common cause of
blindness, kidney failure, and lower limb amputations in adults. Pre-diabetes,
which causes no symptoms, affects about 54 million adults in the
United States
, many of whom will develop type 2 diabetes in the
next 10 years. Pre-diabetes raises the risk of a heart attack or stroke even if
diabetes does not develop. People with pre-diabetes can often prevent or delay
diabetes if they lose a modest amount of weight by cutting calories and
increasing physical activity. People with diabetes also benefit from diet and
exercise as well as medications that control blood glucose, blood pressure, and
cholesterol. For information about the causes, prevention, and treatment of
diabetes, see http://diabetes.niddk.nih.gov/.
Most
NHANES participants with diabetes had type 2 diabetes, which
accounts for up to 95 percent of diabetes cases in the
United States
. Type 2 diabetes usually appears after age 40, and is more common in
overweight, inactive people and in those with a family history of diabetes.
Hearing
loss is a common problem caused by aging, disease, heredity, and noise. About 17
percent of American adults — 36 million people — report some degree of
hearing loss. There is a strong relationship between age and reported hearing
loss: 8 percent of American adults 18 to 44 years old, 19 percent of adults 45
to 64 years old, and 30 percent of adults 65 to 74 years old report trouble with
hearing. For information about the causes and treatment of hearing loss, see
http://www.nidcd.nih.gov/health/hearing/.
The NIDDK
conducts and supports research in diabetes and other endocrine and metabolic
diseases; digestive diseases, nutrition, and obesity; and kidney, urologic, and
hematologic diseases. Spanning the full spectrum of medicine and afflicting
people of all ages and ethnic groups, these diseases encompass some of the most
common, severe, and disabling conditions affecting Americans. For more
information about NIDDK and its programs, see www.niddk.nih.gov.
The
NIDCD supports and conducts research and research training on the normal and
disordered processes of hearing, balance, smell, taste, voice, speech and
language and provides health information, based upon scientific discovery, to
the public. For more information about NIDCD programs, see www.nidcd.nih.gov.
The
National Institutes of Health (NIH) — The
Nation's Medical Research Agency — includes 27 Institutes and
Centers and is a component of the U.S. Department of Health and Human Services.
It is the primary federal agency for conducting and supporting basic, clinical
and translational medical research, and it investigates the causes, treatments,
and cures for both common and rare diseases. For more information about NIH and
its programs, visit www.nih.gov
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