Glycation
Glycation is the covalent attachment of a sugar to a protein, lipid or nucleic acid molecule. Typical sugars that participate in glycation are glucose, fructose, galactose, and their derivatives. Glycation is the non-enzymatic process responsible for many complications in diabetes mellitus and is implicated in other diseases and in aging.
In contrast with glycation, glycosylation is the enzyme-mediated ATP-dependent attachment of sugars to a protein or lipid. Glycosylation occurs at defined sites on the target molecule. It is a common form of post-translational modification of proteins and is required for the functioning of the mature protein.
Biochemistry
Glycations occur mainly in the bloodstream to a small proportion of absorbed simple sugars. Fructose has approximately ten times the glycation activity of glucose, the primary body fuel. Glycation can occur through Amadori reactions, Schiff base reactions, and Maillard reactions; which lead to advanced glycation end products.Biomedical implications
Red blood cells have a consistent lifespan of 120 days and are accessible for measurement of glycated hemoglobin. Measurement of HbA1c—the predominant form of glycated hemoglobin—enables medium-term blood sugar control to be monitored in diabetes.Some glycation products are implicated in age-related chronic diseases, including cardiovascular diseases and Alzheimer's disease.
Long-lived cells, long-lasting proteins, and DNA can sustain substantial glycation over time. Damage by glycation results in stiffening of the collagen in blood vessel walls, increasing blood pressure, especially in diabetes. Glycations also cause weakening of the collagen in blood vessel walls, which may lead to micro- or macro-aneurysm; or strokes if in the brain.
A 2025 study reported that a combination of nicotinamide, ⍺-lipoic acid, thiamine, pyridoxamine, and piperine reduced glycation damage in cell and mice models accompanied by non-muscle weight loss, apparently due to reduced Ghrelin and AMPK production.