Although accurate and convenient for detecting type 2 diabetes and
prediabetes in adults, current HbA1c cutoffs may not be enough to diagnose
diabetes in children.
A 2010 clinical practice guideline from the American Diabetes
Association recommends that physicians exclusively use the HbA1c assay to
detect diabetes. The guidelines recommend a cutoff of 6.5% or greater for
However, researchers for two recent studies highlight significant
vulnerabilities in the recommended test’s ability to diagnose diabetes and
prediabetes in children.
Joyce Lee, MD, MPH, and colleagues at CS Mott Children’s
Hospital and the University of Michigan found sharp contrasts in the efficacy
of the HbA1c assay for detecting
2 diabetes in children vs. adults.
Joyce Lee, MD, MPH
The researchers evaluated the testing results of 1,156 overweight and
obese adolescents aged 12 to 18 years. They compared the efficacy of detecting
diabetes and prediabetes via fasting plasma glucose and 2-hour plasma glucose
vs. various HbA1c cutoffs. When compared with FPG measurements of at least 126
mg/dL, a HbA1c cutoff of 6.5% yielded a 75% sensitivity for diagnosing type 2
diabetes. Lowering the cutoff to 5.7% yielded an even lower sensitivity of 5%.
“Our study provided evidence that the HbA1c test doesn’t work
as well in kids as it does in adults,” Lee told Endocrine Today.
The ADA recommends screening only obese and overweight children because
their weight puts them at a higher risk for developing diabetes. According to
the guidelines, individuals without symptoms would be classified as having
diabetes if HbA1c values reach 6.5% and as having prediabetes if HbA1c values
reach between 6% and 6.4% on two separate tests. These results suggest that the
cutoff point may need to be even lower for children, the researchers said.
“Recommendations may need to be reconsidered for children,”
Two tests better than one?
A study conducted by researchers at Children’s Mercy Hospital in
Kansas City, Mo., found that using the HbA1c test alone missed more than
two-thirds of children at high-risk for type 2 diabetes. However, using two
tests — the HbA1c and the oral glucose tolerance test — dramatically
reduced the risk for delayed diagnosis in overweight children.
Results of a retrospective chart review of 629 overweight children and
adolescents who had both tests were presented at the 2011 Pediatric Academic
Societies Annual Meeting. Data show that 40% of adolescents with type 2
diabetes and 67% of adolescents at high-risk for diabetes using the OGTT would
have shown a normal glycemic status if only the HbA1c test was used for
diagnosis. In addition, nearly nine of 10 patients (86%) had normal glucose
levels according to their HbA1c results.
“Our research indicates that special consideration may need to be
given to overweight children being tested for diabetes,” Ghufran S.
Babar, MD, a pediatric endocrinologist at Children’s Mercy Hospital,
said in a press release. “Simply following the guidelines may not be
enough to ensure these children get proper care.”
Determining the optimal test
While the HbA1c may be a useful tool to try to identify children with
diabetes, Lee said she disagrees with exclusive use in the clinical setting.
Its use in children is further complicated, coupled with the fact that HbA1c
levels rise with age and differ among races/ethnicities, making broad
“Glucose measurements still have a very important role, and I
don’t think those can be discounted, but I would suggest that if a
clinician is going to use HbA1c he or she should use a FPG or 2-hour OGTT as
well,” she said in the interview.
Babar expressed similar sentiments, noting that combining the two tests
may produce accurate results compared with HbA1c alone. – by Melissa
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Disclosure: Drs. Babar and Lee report no relevant financial