HbA1b

HbA1b is a glycated derivative of hemoglobin A (HbA) that can arise when glucose reacts non-enzymatically with the N-terminal valine of the beta chain of HbA. It is part of a group of early glycated Hb species, including HbA1a, HbA1b, HbA1c, and HbA1d, that can be detected by certain older and some specialized chromatographic methods.

Formation and characteristics

The glycated HbA1b fraction forms through non-enzymatic glycation as red blood cells are exposed to circulating glucose. The process is related to the Maillard reaction and reflects the duration and intensity of hyperglycemia. HbA1b tends to comprise a small portion of the total glycated Hb, and its relative abundance can vary with individual glucose exposure, red cell lifespan, and the analytical method used to measure glycated species.

Clinical relevance

HbA1b is not a standard clinical biomarker used in routine practice. HbA1c remains the primary measure for long-term glycemic control in diabetes management. In some laboratory methods, HbA1a, HbA1b, and HbA1c fractions may be reported together or separately; the presence of HbA1a/b can influence the interpretation of HbA1c results in certain assays, particularly those that do not fully separate the different glycated species. Standardized testing approaches and method-specific reporting are important for accurate interpretation.

See also: HbA1c, Hemoglobin A, Hemoglobin A2.