The Amadori Rearrangement Product is the first stable adduct formed during glycation (nonenzymatic glycosylation) of protein. This review deals with the structure of the Amadori adduct on protein, factors affecting the kinetics and specificity of glycation of protein, measurements of the extent of glycation of proteins in vivo, and the possible significance of glycation itself, versus post-glycation reactions, in the development of pathophysiology in diabetes.