HbA1c test misses many cases of pediatric diabetes

December 1, 2011

Using a simple, nonfasting blood test to screen children for diabetes may be too good to be true. A new study found that hemoglobin A1c is not very effective for diagnosing diabetes in children and misses as many as 2 out of 3 cases. What tests did the researchers recommend instead?

Using a simple, nonfasting, blood test to screen children for diabetes may have seemed too good to be true. Now, it turns out that it was.

A new study published in the journal Diabetes Care found that hemoglobin A1c is not very effective for diagnosing diabetes in children and misses many cases. Instead the researchers recommend using the old standbys-random glucose or the nonfasting 1-hour glucose challenge test.

In 2009, the American Diabetes Association (ADA) recommended that HbA1c be exclusively used for the diagnosis of diabetes in children. Organizations such as the American Academy of Pediatrics, however, did not endorse HbA1c as the exclusive measure.

"We found that hemoglobin A1c is not as reliable a test for identifying children with diabetes or children at high risk for diabetes compared with other tests in children," said Joyce M. Lee, MD, MPH, lead researcher for the study and a pediatric endocrinologist at the University of Michigan’s C.S. Mott Children's Hospital. "In fact, it failed to diagnose 2 out of 3 children participating in the study who truly did have diabetes."

The study involved 254 overweight children and adolescents (BMI ≥85th percentile) aged from 10 to 17 years, evenly divided by sex. Less than half the participants had diabetes or prediabetes, 1.2% and 39%, respectively.

Researchers had the participants visit a clinical research unit twice. At the first visit, they arrived fasting and were given a 2-hour glucose tolerance test; HbA1c and fructosamine also were measured. At the second visit, they arrived nonfasting and had a random plasma glucose, a 1-hour 50-g nonfasting glucose challenge test, and urine dipstick performed.

HbA1c, urine dipstick, and fructosamine testing all were found to be less effective in detecting glycemic issues than the other 2 tests-random glucose and the 1-hour glucose challenge tests.

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