The Maillard reaction (nonenzymatic browning) leads through early stage products such as Schiff base and Amadori adduct to advanced glycation end products (AGEs). AGE crosslinks of the Maillard reaction are formed under physiological conditions in a living organism on a variety of blood constituents, on long-lived connective tissues and matrix components. Recently evidence has accumulated that AGE crosslinks as the final products of the Maillard reaction have been suggested as factors in diabetic complications and the ageing process.