Diabetes in adolescents not accurately diagnosed by HbA1c test, study says

Glycated hemoglobin (HbA_1c) may now be internationally accepted for diagnosing and monitoring diabetes, but it appears to be far less accurate for use in adolescents than adults, according to a new study.

Researchers caution that more studies are needed until HbA_1c can confidently be used to diagnose diabetes and prediabetes in adolescents. Earlier this year, the World Health Organization (WHO) formally accepted the use of HbA_1c for the diagnosis of diabetes, calling it a “practical method” that does not always require a patient to fast before a blood sample or to consume an unpalatable glucose drink.

In the study of adolescent diagnosis, patients were defined as having diabetes (fasting plasma glucose [FPG], ≥126 mg/dL; 2-hour plasma glucose [2-hr PG], ≥200 mg/dL) or prediabetes (100 mg/dL ≤ FPG <126 mg/dL; 140 ≤ 2-hr PG <200 mg/dL). Receiver operator character (ROC) analyses were used to evaluate HbA_1c test performance.

Researchers reported that in assessing FPG to detect diabetes, an HbA_1c of 6.5% had sensitivity rates of 75% (30.1%-95.4%) and 53.8% (47.4%-60%) and specificity rates of 99.9% (99.5%-100%) and 99.5% (99.3%-99.6%) for adolescents and adults, respectively. Additionally, when assessing FPG to detect prediabetes, an HbA_1c of 5.7% had sensitivity rates of 5.0% (2.6%-9.2%) and 23.1% (21.3%-25%) and specificity rates of 98.3% (97.2%-98.9%) and 91.1% (90.3%-91.9%) for adolescents and adults, respectively.

According to the investigators, ROC analyses suggested that HbA_1c was a poorer predictor of diabetes mellitus (area under the curve [AUC], 0.88 vs 0.93) and prediabetes (FPG AUC, 0.61 vs 0.74) for adolescents compared with adults. Accuracy was no better when 2-hr PG measurements were used, they said.

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