A laboratory standpoint on the role of hemoglobin A1c for the diagnosis of diabetes in childhood: more doubts than certainties?

The American Diabetes Association has recently included the measurement of hemoglobin A1c (A1c) among the criteria for diagnosing diabetes, so that this diagnostic strategy might also be extended in childhood and adolescence. Although the possibility of using A1c testing for screening and even diagnosing diabetes is highly appealing, A1c testing cannot be considered as yet the 'panacea' for a variety of reasons that include the suboptimal correlation with the mean blood glucose, the risk of misdiagnosis in children or adolescents with impaired renal function, iron-deficiency anemia and increased red blood cell turnover, the interference from hemoglobin variants, and the heterogeneous diagnostic performance among different populations. Additional limitations include the higher imprecision of most A1c assays (especially point-of-care testing devices) when compared with plasma glucose measurement, as well as the incremental cost deriving from routinely replacing plasma glucose with A1c determination. Taken together, the current limitations would suggest a certain degree of caution before recommending the widespread implementation of the A1c assay for diagnosing diabetes in childhood and adolescence. The potential clinical benefits (if any) of replacing blood glucose testing with A1c for diagnosing diabetes are still uncertain and will probably remain so until reliable cost-effective analyses are available.