|Tight Glucose Control Lowers CVD
by About 50 Percent in Diabetes
A significantly lower risk of heart disease can now
be added to the list of proven long-term benefits of
tight glucose control in people with type 1 diabetes.
Researchers announced this finding today at the annual
scientific meeting of the American Diabetes Association
after analyzing cardiovascular (CVD) events such as
heart attack, stroke, and angina in patients who took
part in the Diabetes Control and Complications Trial
(DCCT) years ago.
“The longer we follow patients, the more we’re impressed
by the lasting benefits of tight glucose control,” said
Saul Genuth, M.D., of Case Western University. Dr. Genuth
chairs the follow-up study of DCCT participants, called
the Epidemiology of Diabetes Interventions and Complications
(EDIC) study, which has been looking at the long-term
effects of prior intensive versus conventional blood
glucose control. “The earlier intensive therapy begins
and the longer it is maintained, the better the chances
of reducing the debilitating complications of diabetes.”
The DCCT was a multicenter study that compared intensive
management of blood glucose to conventional control
in 1,441 people with type 1 diabetes. Patients 13 to
39 years of age were enrolled in the trial between 1983
and 1989. Those randomly assigned to intensive treatment
kept glucose levels as close to normal as possible with
at least three insulin injections a day or an insulin
pump, guided by frequent self-monitoring of blood glucose.
Intensive treatment meant keeping hemoglobin A1c (HbA1c)
levels as close as possible to the normal value of 6
percent or less. (The HbA1c blood test reflects a person’s
average blood sugar over the past 2 to 3 months.) Conventional
treatment at the time consisted of one or two insulin
injections a day with daily urine or blood glucose testing.
In 1993, researchers announced the DCCT’s main findings:
intensive glucose control greatly reduces the eye, nerve,
and kidney damage of type 1 diabetes. Tight control
also lowers the risk of atherosclerosis, according to
a study of DCCT participants published in 2003. But
what’s most remarkable about intensive control, the
researchers say, is its long-lasting value.
After 6½ years of the DCCT, HbA1c levels averaged
7 percent in the intensively treated group and 9 percent
in the conventionally treated group. When the study
ended, the conventionally treated group was encouraged
to adopt intensive control and shown how to do it, and
researchers began the long-term follow-up of participants.
To the researchers’ surprise, the benefits of the original
6 years of intensive control have persisted despite
the fact that both groups' HbA1c values have leveled
off at about 8 percent after a rise in blood glucose
in the intensively treated group and a drop in blood
glucose in those formerly on conventional treatment.
In results announced today, among the 1,375 volunteers
continuing to participate in the study, the intensively
treated patients had less than half the number of CVD
events than the conventionally treated group (46 compared
to 98 events). Such events included heart attacks, stroke,
angina, and coronary artery disease requiring angioplasty
or coronary bypass surgery. Thirty-one intensively treated
patients (4 percent) and 52 conventionally treated patients
(7 percent) had at least one CVD event during the 17
years of follow-up. The average age of participants
is 45 years; 53 percent are male.
“The risk of heart disease is about 10 times higher
in people with type 1 diabetes than in people without
diabetes. It’s now clear that high blood glucose levels
contribute to the development of heart disease,” said
David Nathan, M.D., of Massachusetts General Hospital,
who co-chaired the DCCT/EDIC research group and presented
the results. “The good news is that intensively controlling
glucose significantly reduces heart disease as well
as damage to the eyes, nerves, and kidneys in people
with type 1 diabetes. Tight control is difficult to
achieve and maintain, but its advantages are huge.”
“The take-home message is that good glucose control
should be started as early as possible to delay or prevent
serious diabetes-related complications,” said Alan D.
Cherrington, PhD, president, American Diabetes Association.
Is glucose control just as important for people with
type 2 diabetes? “There is a strong and growing body
of evidence that everyone with diabetes gains from strict
blood glucose control,” said Catherine Cowie, PhD, who
oversees EDIC for the National Institute of Diabetes
and Digestive and Kidney Diseases (NIDDK).
DCCT and EDIC were funded by the NIDDK and other parts
of the National Institutes of Health (NIH) under the
Department of Health and Human Services. Genentech,
Inc., also supported the studies through a Cooperative
Research and Development Agreement with the NIDDK. The
NIH also funds a great deal of research aimed at developing
new approaches to help patients control diabetes, which
is difficult for many people.
About 18.2 million people in the United States have
diabetes, the most common cause of blindness, kidney
failure, and amputations in adults and a major cause
of heart disease and stroke. At least 65 percent of
people with diabetes will die from a heart attack or
stroke, yet two out of every three people with diabetes
are unaware of their increased risk.
Type 1 diabetes accounts for up to 10 percent of diagnosed
cases of diabetes in the United States (up to 1 million
people). This form of diabetes usually strikes children
and young adults, who need several insulin injections
a day or an insulin pump to survive. Insulin, though critical
for controlling blood glucose, is no cure. Most people
with type 1 diabetes eventually develop one or more complications,
including damage to the heart and blood vessels, eyes,
nerves, and kidneys.
In its "Be Smart About Your Heart: Control the ABCs
of Diabetes" campaign, the National Diabetes Education
Program (www.ndep.nih.gov/), jointly sponsored by the
NIH, the Centers for Disease Control and Prevention,
and 200 partner organizations including the American
Diabetes Association (ADA), encourages people with diabetes
to control their blood glucose as well as their blood
pressure and cholesterol. By keeping all three as close
to normal as possible, people with diabetes can live
long, healthy lives.
“Make the Link! Diabetes, Heart Disease and Stroke,” is
a joint initiative of the American Diabetes Association
(www.diabetes.org/makethelink) and the American College
of Cardiology (www.acc.org), which works to increase
awareness of the link between diabetes and heart disease
and help educate physicians and people with diabetes
about how to reduce those risks.
The National Institutes of Health (NIH) The
Nation's Medical Research Agency is comprised
of 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 investigates the causes, treatments,
and cures for both common and rare diseases. For more
information about NIH and its programs, visit www.nih.gov.