City of Hope Study Finds Popular Diabetes Diagnosis Test Misses Most Cases

The hemoglobin A1c blood test is widely used to diagnose type 1 and type
2 diabetes, but it is actually unable to detect the disease in most
patients, according to a new study presented Saturday, March 23, at a
news conference at ENDO 2019, the Endocrine Society’s annual meeting in
New Orleans, La.

“Based on these findings, A1c should not be solely used to rule out
diabetes, particularly if a patient has prediabetes or has increased
risk factors for developing diabetes,” said lead researcher Maria
Mercedes Chang Villacreses, M.D., of City of Hope’s Diabetes
and Metabolism Research Institute, who presented at the press
conference. “It should be used in conjunction with the oral glucose test
for increased accuracy.”

Led by Ken C. Chiu, M.D., City of Hope professor of clinical diabetes,
endocrinology & metabolism, the study included 9,000 adults from the
2005-2014 National Health and Nutrition Examination Survey who did not
have a diabetes diagnosis. The participants received both an A1c test
and an oral tolerance glucose test, and the researchers compared the
results. The researchers found the A1c test didn’t catch 73 percent of
diabetes cases that were detected by the oral glucose test.

“The A1c test showed these people had normal glucose levels when they
didn’t,” Chang Villacreses said.

The hemoglobin A1c test, also known as HbA1c, shows a person’s average
level of blood sugar over the past two to three months. The test is used
to diagnose diabetes, and also to find out whether a person with the
disease has blood sugar levels within a certain target range. The simple
blood test has grown in popularity because it doesn’t require patients
to fast, unlike the two other most common diabetes tests.

The oral glucose tolerance test measures the body's response to sugar
(glucose). In this test, a person’s blood is taken after an overnight
fast, and then again two hours after they drink a sugary drink. The
glucose tolerance test can be used to screen for type 2 diabetes.

The researchers also found race and ethnicity had a significant impact
on the accuracy of A1c. It was more likely to detect abnormal glucose
levels in non-Hispanic whites than in non-Hispanic blacks or Hispanics.

“We want to diagnose diabetes earlier so we can intervene earlier and
potentially prevent diabetic complications from developing,” Chang
Villacreses said. “The best way to do that is by also using oral glucose
tests.”

According to the Centers for Disease Control and Prevention, 30.3
million U.S. adults have diabetes, and one in four of them don’t know
they have it. Diabetes is the seventh leading cause of death in the
United States, and is the leading cause of kidney failure, lower-limb
amputations and adult blindness. In the last 20 years, the number of
adults diagnosed with diabetes has more than tripled.

City of Hope’s legacy in diabetes research is extensive. Human
synthetic insulin was developed as a result of technology developed
at City of Hope (led by Arthur Riggs, Ph.D., and Keiichi Itakura, Ph.D.)
and the institution’s scientists (led by Samuel
Rahbar, M.D., Ph.D.) also first reported elevated HbA1c levels in
patients with diabetes, both seminal findings in diabetes that have
impacted millions of people worldwide. Most recently, The
Wanek Family Project for Type 1 Diabetes at City of Hope aims to
create powerful new approaches to curing type 1 diabetes.

About City of Hope

City of Hope is an independent biomedical research and treatment center
for cancer, diabetes and other life-threatening diseases. Founded in
1913, City of Hope is a leader in bone
marrow transplantation and immunotherapy such as CAR
T cell therapy. City of Hope’s translational research and
personalized treatment protocols advance care throughout the world.
Human synthetic insulin and numerous
breakthrough cancer drugs are based on technology developed at the
institution. A National Cancer Institute-designated comprehensive cancer
center and a founding member of the National Comprehensive Cancer
Network, City of Hope is ranked one of America's "Best Hospitals" in
cancer by U.S. News & World Report. Its main campus is located near Los
Angeles, with additional
locations throughout Southern California. For more information about City
of Hope, follow us on Facebook, Twitter, YouTube or Instagram.

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