Abstract
Hemoglobin (Hb)A1c is a marker of long-term glycemic control in patients with diabetes. At the 69th Scientific Sessions of the American Diabetes Association, it was announced that the diagnosis of diabetes may be conveniently based on HbA1c ≥6.5%, without the need to measure plasma glucose concentration (International Expert Committee in Diabetes Care 32:1327–1334, 2009). However, we experienced two cases of high HbA1c levels with normal glucose tolerance confirmed by 75 g oral glucose tolerance test (75 g OGTT); thus, these cases might have been misdiagnosed as diabetes if we had not measured plasma glucose levels. If HbA1c is used as the sole means of diagnosis and assessing the glycemic state, some patients with hemoglobinopathy will be misdiagnosed as having diabetes, which could lead to unnecessary treatment. Importantly, medical staff should be aware of the limitations of measurement of HbA1c by the HPLC method with respect to interference with Hb variants. Concomitant use of other glycemic markers such as plasma glucose or glycoalbumin is recommended when the value of HbA1c is considered unreliable.
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References
International Expert Committee. International Expert Committee report on the role of the A1C assay in the diagnosis of diabetes. Diabetes Care. 2009;32:1327–34.
Seino Y, Nanjo K, Tajima N, Kadowaki T, Kashiwagi A, et al. Report of the Committee on the classification and diagnostic criteria of diabetes mellitus. The Committee of the Japan Diabetes Society on the diagnostic criteria of diabetes mellitus. Diabetol Int. 2010;1:2–20.
Harano T, Harano K, Kawasaki R, Kawakami K. Hb Toranomon [beta 112(G14)Cys→Trp]: a new unstable electrophoretically silent hemoglobin. Hemoglobin. 1996;20:361–9.
Server. GG: Hb Var: a database of human hemoglobin variants and thalassemias. http://globin.bx.psu.edu/hbvar/menu.html (2010). Accessed 3 Nov 2010.
John WG. Glycated haemoglobin analysis. Ann Clin Biochem. 1997;34(Pt 1):17–31.
Bry L, Chen PC, Sacks DB. Effects of hemoglobin variants and chemically modified derivatives on assays for glycohemoglobin. Clin Chem. 2001;47:153–63.
Shimizu A, Nakanishi T, Miyazaki A. Detection and characterization of variant and modified structures of proteins in blood and tissues by mass spectrometry. Mass Spectrom Rev. 2006;25:686–712.
Little RR, Rohlfing CL, Hanson S, Connolly S, Higgins T, Weykamp CW, D’Costa M, Luzzi V, Owen WE, Roberts WL. Effects of hemoglobin (Hb) E and HbD traits on measurements of glycated Hb (HbA1c) by 23 methods. Clin Chem. 2008;54:1277–82.
Little RR, Roberts WL. A review of variant hemoglobins interfering with hemoglobin A1c measurement. J Diabetes Sci Technol. 2009;3:446–51.
Harano T. Hemoglobinopathy in Japan: detection and analysis. Rinsho Byori. 1999;47(3):215–23.
Takarabe D, Kishimoto M, Tanaka T, Takahashi Y, Kajio H, Harano K, Noda M. Hemoglobin variant HbE found in two South Asian diabetic patients. Intern Med. 2009;48:1397–401.
Gillett MJ. International Expert Committee report on the role of the A1c assay in the diagnosis of diabetes: Diabetes Care 2009; 32(7): 1327–1334. Clin Biochem Rev. 2009;30:197–200.
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Tomita, M., Kabeya, Y., Okada, K. et al. Normal glucose tolerance with high HbA1c levels observed in two cases of Hb variants. Diabetol Int 1, 104–107 (2010). https://doi.org/10.1007/s13340-010-0016-5
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DOI: https://doi.org/10.1007/s13340-010-0016-5