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Licensed Unlicensed Requires Authentication Published by De Gruyter May 14, 2019

Trueness assessment of HbA1c routine assays: are processed EQA materials up to the job?

  • Vincent Delatour EMAIL logo , Noémie Clouet-Foraison , Stéphane Jaisson , Patricia Kaiser and Philippe Gillery



With the worldwide increase of diabetes mellitus prevalence, ensuring that HbA1c assays are accurate is essential. External quality assessment (EQA) programs enable laboratories to verify that analytical methods perform according to the manufacturers’ specifications. However, assessing trueness requires commutable materials, a property that is rarely characterized for EQA materials.


The difference in bias approach was used to assess commutability of 26 processed quality control materials for 17 of the most frequently used HbA1c assays. Involved assays included immuno-assays, enzymatic assays, affinity, ion-exchange HPLC boronate affinity HPLC and capillary electrophoresis. The measurements were performed at manufacturers or expert laboratories. Assay trueness was additionally assessed against the IFCC reference measurement procedure using fresh clinical specimens that were distributed to 450 medical laboratories.


Commutability of processed EQA materials was highly heterogeneous and globally insufficient to rigorously assess the trueness of HbA1c assays. Using fresh clinical specimens, mean bias was −0.13 mmol/mol for low HbA1c (34 mmol/mol), between +1.0 and +1.3 mmol/mol for intermediate HbA1c (49 and 58 mmol/mol) and +1.2 mmol/mol for elevated HbA1c (90 mmol/mol).


This study demonstrates that due to insufficient commutability, most processed EQA materials are unsuitable to assess trueness of HbA1c assays and agreement between the different assays. These materials can only provide information on comparability of individual laboratory results with its peers and on assay precision. Using fresh whole blood samples, this study additionally shows that most HbA1c assays are fairly accurate and meet the total allowable error quality target of 5 mmol/mol.

Corresponding author: Dr. Vincent Delatour, Laboratoire National de Métrologie et d’Essais (LNE), 1 rue Gaston Boissier, 75724 Paris Cedex 15, France, Phone: +33 140 434 075
aVincent Delatour and Noémie Clouet-Foraison contributed equally to the writing of this article.


We thank EQA providers and manufacturers of quality control materials having shared the materials which commutability was assessed in this study.

  1. Author contributions: All the authors have accepted responsibility for the entire content of this submitted manuscript and approved submission.

  2. Research funding: None declared.

  3. Employment or leadership: None declared.

  4. Honorarium: None declared.

  5. Competing interests: The funding organization(s) played no role in the study design; in the collection, analysis, and interpretation of data; in the writing of the report; or in the decision to submit the report for publication.


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Supplementary Material

The online version of this article offers supplementary material (

Received: 2019-02-25
Accepted: 2019-04-07
Published Online: 2019-05-14
Published in Print: 2019-09-25

©2019 Walter de Gruyter GmbH, Berlin/Boston

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