[Glucose and its protein environment in vivo]

The non-enzyme reaction by which glucose can combine with free amines has been known since the beginning of the century: in 1912, Mallard reported the combination of glucose with amino acids. This reaction results in the formation of cetoamine or fructosamine as well as often complex sub-products responsible for a change in the color of the medium that turns brown. This process, which food chemists are well-familiar with, was not observed in vivo until three-quarters of a century later. In 1975, hemoglobin A was shown to combine with glucose by means of a non-enzyme reaction, producing hemoglobin A1c. HbA1c is now believed to be a "black box", i.e. a cumulative reflection of all the hyperglycemic episodes that occurred over the last hundred days. This discovery was followed by an impressive number of similar observations: nearly all the available amines seem able to participate in this kind of reaction. Plasma proteins, membrane proteins, structural proteins such as collagen, the apolipoproteins of circulating lipoproteins, intracellular tubulines, and even nucleic acids seem capable of undergoing glycation. A great number of bioclinica uses of this phenomenon have already been developed. Diabetes mellitus has benefited most from these investigations and, from a broader viewpoint, studies in this field are unquestionably central to our understanding of atherosclerosis, inflammation, and cancer. Furthermore, the entire spectrum of these observations are related to ageing.