Glycated hemoglobin

Glycated hemoglobin (commonly referred to as HbA1c) is a form of hemoglobin (Hb) that is chemically linked to a sugar, usually glucose. This process, known as glycation, occurs when glucose in the bloodstream attaches to the hemoglobin molecule non-enzymatically, i.e., spontaneously without the help of an enzyme.

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Glycated

Biochemical Basis

Monosaccharides such as glucose, galactose, and fructose can spontaneously bond with hemoglobin when present in the bloodstream. However, glucose is less likely to do so than galactose and fructose, which may explain why glucose is used as the primary metabolic fuel in humans.

Clinical Significance

The percentage of glycated hemoglobin in an individual's blood is directly proportional to the average blood glucose concentration over the previous three months, which is the lifespan of a red blood cell. Therefore, HbA1c is a useful long-term marker of blood glucose control and is used as a diagnostic and monitoring tool in the management of diabetes mellitus.

Testing and Interpretation

HbA1c levels are typically measured by blood tests conducted in a clinical laboratory. An HbA1c level of 6.5% or higher on two separate tests indicates diabetes. A result between 5.7% and 6.4% is considered prediabetes.

See Also

• Hemoglobin
• Diabetes mellitus
• Prediabetes

References

Glycated hemoglobin Resources
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