Hb A1c: a review on its structure, biosynthesis, clinical significance and methods of assay.

Normal red blood cells contain, in addition to the major hemoglobin (Hb A) some minor fractions as Hb A2 and glycosylated hemoglobins: Hb A1a, Hb A1b, Hb A1c. The study of the glycosylated hemoglobins has been greatly stimulated by the observation that their proportion was increased in diabetes mellitus. This paper sums up the more recent knowledge on the structure of the minor fractions, and mainly on Hb A1c. Biosynthesis of these hemoglobins is also considered. Since the glycosylated hemoglobins has raised a great interest, different techniques were designed for its assay: chemical, chromatographic and immunological techniques and isoelectric focusing. In this paper, these different methods are reviewed and compared.