Glycated hemoglobin

Glycated hemoglobin (old name glycosylated hemoglobin) is formed by a non-enzymatic reaction between hemoglobin and blood glucose. The reaction is irreversible.

Glycation pathway

Glycated hemoglobin levels, therefore, reflects blood glucose levels throughout the life of the erythrocyte, about 120 days, and are used to assess the success of diabetes treatment/compensation in the 4 - 8 weeks before the examination. We most often determine the stabile fraction of HBA_1c.

Terminology

• Glycated hemoglobin - the sum of carbohydrate adducts at the N-terminus or ε amino groups of lysine in hemoglobin.

• HbA₁ – the sum of various minor hemoglobin fractions (glycated), including HbA_1c, HbA_1a1/a2, HbA_1b1/b2/b3, HbA_1d1/d2/d3 and HbA_1e.

• HbA_1c – glucose adduct of valine at the N-terminus of β-globin; corresponds to the so-called stable ketoamine (N- [1-deoxyfructosyl] hemoglobin).

Glycated hemoglobin can be determined by ion-exchange chromatography followed by spectrophotometry.

Evaluation

The amount of glycated hemoglobin is expressed in % of total hemoglobin or now in mmol/mol according to the IFCC (International Federation of Clinical Chemistry).

Reference limits

• in healthy adults up to 39 mmol/mol, (2.8 – 4.0%)
• In diabetics, HbA 1c concentrations of up to 45 mmol/mol (4.5 %) indicate excellent diabetes compensation, up to 60 mmol/mol (6.0 %) of acceptable and higher values ​​of unsatisfactory diabetes compensation.

References

Related articles

Hemoglobin

Hemoglobinopathies

Sources

1. ČEŠKA, Richard and Tomáš ŠTULC, et al. Internal. 2nd edition. TRITON, 2022. 870 pp.  ISBN 978-80-7387-885-6 .
2. ↑ Recommended diagnostic and treatment procedures for general practitioners. Diabetes mellitus . 2005. Also available from URL < https://www.svl.cz/files/files/Doporucene-postupy-2003-2007/Diabetes-mellitus.pdf >.