|Diabetic Retinopathy Occurs in Pre-Diabetes
Diabetic retinopathy has been found in nearly 8 percent
of pre-diabetic participants in the Diabetes Prevention
Program (DPP), according to a report presented today
at the American Diabetes Association's 65th Annual Scientific
Sessions. Diabetic retinopathy, which can lead to vision
loss, was also seen in 12 percent of participants with
type 2 diabetes who developed diabetes during the DPP.
No other long-term study has evaluated retinopathy in
a population so carefully examined for the presence
or development of type 2 diabetes.
“These findings reinforce the recommendation that patients
with newly diagnosed type 2 diabetes should be screened
for retinopathy,” said Emily Chew, M.D., of the National
Eye Institute, part of the National Institutes of Health
(NIH) under the U.S. Department of Health and Human
Services, which funded the study. “We advise good control
of blood glucose, blood pressure, and cholesterol as
well as regular eye exams.”
“Previous studies have not accurately defined when
type 2 diabetes begins, so our understanding of the
onset of diabetic eye disease has been limited. Now
we know that diabetic retinopathy does occur in pre-diabetes.
We’re also seeing it early in the course of diabetes — within
an average of 3 years after diagnosis,” noted Richard
Hamman, M.D., DrPH, professor and chair, Department
of Preventive Medicine and Biometrics, University of
Colorado School of Medicine, and vice chair of the DPP. “This
adds to our understanding of the development of retinopathy
and suggests that changes in the eye may be starting
earlier and at lower glucose levels than we previously
Pre-diabetes is a condition in which blood glucose
levels are higher than normal but not high enough for
a diagnosis of diabetes. The condition is sometimes
called "impaired fasting glucose (IFG)" or "impaired
glucose tolerance (IGT)," depending on the test used
to diagnose it. People with pre-diabetes have an increased
risk of developing type 2 diabetes, heart disease, and
Diabetic retinopathy, which begins with changes in
the small vessels in the back of the eye, often leads
to loss of vision. Regular eye examinations to diagnose
retinopathy are recommended for patients with diabetes
because treatment with laser photocoagulation can often
prevent blindness in more advanced cases. Diabetic retinopathy
is still the most common cause of blindness in adults.
(For more information about diabetic retinopathy, see
NEI’s Diabetic Retinopathy: What you should know http://www.nei.nih.gov/health/diabetic/retinopathy.asp).
“Certain retinopathy lesions are considered indicative
of the presence of diabetes because they are the first
retinal changes to develop in this disease,” explained
Dr. Hamman. “Although the retinopathy seen in the DPP
participants was at a very early stage and did not affect
vision, eye changes typical for diabetes were found
in 8 percent of our study population before they developed
diabetes. These observations may lead diabetes experts
to reconsider the diagnostic thresholds used to define
diabetes, which are based on levels of blood glucose
associated with the development of eye, nerve and kidney
complications of diabetes.”
DPP study chair David Nathan, M.D., of Massachusetts
General Hospital, pointed out that the retinopathy results
are based on a random sample of only 12 percent of DPP
participants, all of whom had impaired glucose tolerance,
a form of pre-diabetes, when the study began. “These
initial findings confirm what other studies have suggested.
The complications of diabetes may begin before diabetes
is diagnosed, at least by the current-day standards,” he
explained. “Ideally, an expanded study of the remaining
88 percent of DPP Outcome Study participants might enable
us to define more appropriate diagnostic thresholds.”
About 18.2 million Americans have diabetes, a group
of serious diseases marked by high blood glucose levels
that result from defects in the body's ability to produce
and/or use insulin. Diabetes can lead to severely debilitating
or fatal complications, such as heart disease, blindness,
kidney disease, and amputations. It is the fifth leading
cause of death by disease in the United States. Type
2 diabetes, which accounts for up to 95 percent of all
diabetes cases, involves insulin resistance — the body’s
inability to properly use its own insulin. It usually
occurs in overweight adults, but it has increasingly
been seen in obese children and teens in recent years.
About 40 percent of U.S. adults ages 40 to 74 — 41 million
people — have abnormal blood glucose levels without having
diabetes. Many will develop type 2 diabetes in the next
10 years. (In the DPP, about 10 percent of participants
in the placebo group developed diabetes each year.)
Once a person has type 2 diabetes, the risk of heart
and blood vessel disease is 2 to 4 times that of people
Diabetes Prevention Program
The Diabetes Prevention Program was a major clinical
trial in 3,234 people with impaired glucose tolerance.
The study’s main results were announced in 2001 and
reported in the Feb. 7, 2002 issue of the New England
Journal of Medicine: Losing 5 to 7 percent of body
weight through diet and a modest, consistent increase
in physical activity (e.g., walking 5 days a week
30 minutes a day) lowered the incidence of type 2
diabetes by 58 percent. Treatment with metformin,
an oral drug commonly used to treat diabetes, reduced
the chances of developing diabetes by 31 percent.
The DPP was sponsored by the National Institute of
Diabetes and Digestive and Kidney Diseases (NIDDK) and
co-funded by other components of the NIH, the Centers
for Disease Control and Prevention, and the Indian Health
Service. The American Diabetes Association provided
additional funding. Sources of corporate support included
Bristol-Myers Squibb, Parke-Davis, Merck and Company,
Merck Medco, Hoechst Marion Roussel, Sankyo, Lifescan,
Lipha Pharmaceuticals, Slimfast, Nike, and Health-O-Meter.
About 90 percent of DPP participants continue to be
followed closely in the DPP Outcomes Study to examine
the longer-term impact of the original treatment interventions.
All participants are given access to quarterly lifestyle
group sessions, while those in the original intensive
lifestyle group have access to additional lifestyle
activities to help them stay on track. The participants
originally assigned to metformin therapy continue to
have access to the drug.
Three hundred two, or about 12 percent, of the DPP Outcome
Study participants who had not developed diabetes
during the study, and 588 of 876 participants who
had developed diabetes, were selected to participate
in the retinopathy study, funded by the NEI. To detect
diabetic retinopathy, an evaluation of the fundus
(inner lining of the eye) was performed with a special
camera that provides a detailed look at the retina.
Small changes in the vessels, called microaneurysms
and hemorrhages, signal the development and degree
of retinopathy severity.
Participants with pre-diabetes and retinopathy typically
had a small number of microaneurysms in the eye characteristic
of early, mild retinopathy that is not yet linked to
vision loss. Those who had developed diabetes in the
previous 1 to 5 years had slightly more severe retinopathy.
Higher average blood glucose levels and higher blood
pressure were associated with the risk of developing
retinopathy in the new-onset diabetic patients, similar
to previous findings in people with longstanding diabetes
who develop retinopathy.
In its "Be Smart About Your Heart: Control the ABCs
of Diabetes" campaign, the National Diabetes Education
Program (NDEP) (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.
NDEP’s “Small Steps. Big Rewards. Prevent Type 2 Diabetes” campaign
gives tips on lifestyle changes to prevent or delay
type 2 diabetes.
“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.