At-risk individuals with an HbA1c test level ≥6.1% are more likely to
have undiagnosed diabetes, according to new study findings.
There are many advantages in efficacy of HbA1c vs. fasting glucose
or glucose tolerance testing. Our results provide additional support that HbA1c
can be an effective method to identify undiagnosed diabetes in at-risk
patients, Adit Ginde, MD, MPH, assistant professor of surgery,
division of emergency medicine at the University of Colorado Denver School of
Medicine, told Endocrine Today.
Ginde and colleagues evaluated the predictive validity of HbA1c as a
screening test in 6,723 NHANES 1999-2004 participants. The estimated prevalence
of undiagnosed diabetes (fasting plasma glucose ≥126 mg/dL) in the United
States population was 2.8%, or 5.5 million people.
The researchers derived a risk score for undiagnosed diabetes and
stratified participants into prevalence risk subgroups: low (0.44%), moderate
(4.1%) and high (11.1%).
HbA1c is very effective in screening for undiagnosed diabetes when
patients are stratified into risk groups, Ginde said. Risk factors and
independent predictors of undiagnosed diabetes were older age, male sex, black
race, hypertension, elevated waist circumference, elevated triglycerides and
More than half of high-risk individuals with HbA1c ≥6.1% had
undiagnosed diabetes. Among those with a combination of risk factors, HbA1c
levels as low as 5.4% can signal undiagnosed diabetes, according to Ginde.
Diabetes can be reliably excluded with HbA1c <6.1% in moderate-risk patients
and <5.5% in high-risk patients, he said.
In August, a consensus panel recommended HbA1c testing be used as a
frontline method for identifying patients at risk for diabetes. Additionally,
the panel recommended that HbA1c ≥6.5% be accepted as a criterion for
diagnosing diabetes. These findings suggested an even lower cut-off point.
With any patient, evaluate diabetes risk factor profile and
consider HbA1c as an initial test to screen for undiagnosed diabetes in
moderate- and high-risk patients in nonfasting visits, Ginde said.
by Katie Kalvaitis
J Clin Endocrinol Metab. 2008;93:2447-2453.
J Gen Intern Med. 2008;23:1346-1353.
HbA1c Level Signaling
Diabetes in At-Risk Patients
||Requires confirmatory fasting plasma glucose
|5.5% to 6%
||May exclude diabetes in moderate-risk but not
||May reliably exclude diabetes