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Alarming increase in HbA1c and near misdiagnosis of diabetes mellitus resulting from a clinical laboratory instrument upgrade and haemoglobin variant
  1. Steven D Chessler,
  2. Donald E Lee
  1. Department of Medicine, University of California Irvine, Irvine, California, USA
  1. Correspondence to Dr Steven D Chessler, s.chessler{at}


A 29-year-old woman was referred for new-onset diabetes mellitus after her glycosylated haemoglobin (HbA1c) was found to be 10.2%. Three years earlier, the patient’s HbA1c—measured by the same clinical laboratory—had been 5.5%. The newer HbA1c was discordant with fasting glucose levels and a lack of diabetes-associated symptoms. The laboratory reported that their assay methodology remained unchanged and also that no haemoglobin variants were detected. Further investigation, however, revealed, first, that the patient carried a haemoglobin alpha chain mutation (Hb Wayne) that can sometimes cause assay interference and, second, that although the laboratory’s assay methodology had not changed, their assay instrument had. Depending on assay methodology, haemoglobin variants can cause HbA1c assay interference and the presence of these variants may not be detected by the performing laboratory. Interference may not only be dependent on assay methodology but also on the assay instrument used.

  • diabetes
  • haematology (incl blood transfusion)
  • endocrinology
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  • Contributors SDC undertook the described medical investigations, researched and co-wrote the manuscript. DEL co-wrote and critically edited and revised the manuscript.

  • Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.

  • Competing interests None declared.

  • Patient consent Obtained.

  • Provenance and peer review Not commissioned; externally peer reviewed.

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