HbA_1c May Help Flag Impaired Glucose Tolerance in Children

PHILADELPHIA — Testing for hemoglobin A_1c could be an effective means of screening children not only for type 2 diabetes but also for impaired glucose tolerance, according to the results of a study of 74 children.

“Type 2 diabetes was effectively excluded by hemoglobin A_1c [HbA_1c] below 6.0%,” said Dr. Alisa Schiffman of Children's Hospital of Philadelphia. Using this cut-off, HbA_1c was 100% sensitive and 80% specific in identifying children with type 2 diabetes.

In its 2008 position statement on the standards of medical care in diabetes, the American Diabetes Association stated that the fasting plasma glucose test is the preferred means to diagnose diabetes in children and nonpregnant adults. The use of the HbA_1c level for the diagnosis of diabetes is not recommended at this time (Diabetes Care 2008;31:S12–54).

However, “oral glucose tolerance tests and fasting plasma glucose have logistical challenges in children” because of the overnight fasting requirement and multiple blood draws, Dr. Schiffman said at the annual meeting of the Eastern Society for Pediatric Research. HbA_1c testing can be performed with just a finger stick at any time of day regardless of fasting status.

The researchers performed a retrospective chart review of 74 children (mean age 12 years) who were referred for the evaluation of type 2 diabetes. The children were assigned to one of three groups based on their fasting plasma glucose level and 2-hour plasma glucose level.

There was a significant trend for increasing HbA_1c along the continuum from normal glucose tolerance to type 2 diabetes. Mean HbA_1c was 5.4% for those with normal glucose tolerance, 6.1% for those with impaired glucose tolerance, and 6.8% for those with type 2 diabetes. A threshold HbA_1c of 5.7% was 91% sensitive and 80% specific in identifying children with abnormal glucose tolerance.

“Hemoglobin A_1c can be used to screen for type 2 diabetes and even impaired glucose tolerance [in children],” said Dr. Schiffman.

Likewise, there was a significant trend for decreasing mean β-cell function along the continuum from normal glucose tolerance to impaired glucose tolerance to type 2 diabetes.

There were no significant differences between the groups in terms of gender, age, race, or body mass index. HbA_1c was adjusted for age, gender, ethnicity, and body mass index.