Glycated hemoglobin (HbA1c)

Glycated hemoglobin refers to forms of the oxygen-carrying protein hemoglobin that have been chemically linked to sugars via nonenzymatic glycation reactions. The most clinically relevant form is hemoglobin A1c, which forms when circulating glucose binds covalently to the N-terminal valine residue on the beta chain of adult human hemoglobins. The proportion (%) of total circulating Hb present as HbA1c reflects average plasma glucose concentration over approximately three months—the typical lifespan of erythrocytes—and thus serves as an integrated marker for long-term glycemic status. Measurement of HbA1c plays a central role in diagnosing type 2 diabetes mellitus and prediabetes; it also guides therapy adjustments aimed at reducing risks associated with chronic hyperglycemia such as cardiovascular events and microvascular complications including nephropathy and retinopathy. While no therapies act directly on glycated forms themselves, many classes of antidiabetic medications aim to reduce their formation by lowering systemic blood sugar concentrations.

Other names

GlycohemoglobinGlycosylated hemoglobinHemoglobin A1cHbA1cA1C

Not applicable directly to glycated hemoglobin. For antidiabetic drugs: Mechanisms include increasing insulin secretion/sensitivity or reducing hepatic glucose production to lower overall blood glucose levels; this results in reduced formation of new glycated hemoglobin molecules over time.