糖化（英语：glycation）是在不受酶的控制下，蛋白质或脂质分子上附加糖类分子（如果糖或葡萄糖）的过程。所有的血糖都是还原性分子。非酶糖基化可发生在体内(endogenous glycation)，也可以发生在体外(exogenous glycation)。在酶控制下的蛋白质或脂质上附加糖类的过程称为糖基化（glycosylation）。非酶糖基化是一个随机性的过程，会损害生物分子的功能。而糖基化则发生在靶分子的指定部位，是使分子产生活性的必需过程。 有关果糖的非酶糖基化的早期研究所采用的分析技术不够准确，导致果糖对非酶糖基化的重要性受到了严重低估。

Glycation (sometimes called non-enzymatic glycosylation) is the result of the typically covalent bonding of a protein or lipid molecule with a sugar molecule, such as fructose or glucose, without the controlling action of an enzyme. All blood sugars are reducing molecules. Glycation may occur either inside the body (endogenous glycation) or outside the body (exogenous glycation). Enzyme-controlled addition of sugars to protein or lipid molecules is termed glycosylation; glycation is a haphazard process that impairs the functioning of biomolecules, whereas glycosylation occurs at defined sites on the target molecule and is required in order for the molecule to function. Much of the early laboratory research work on fructose glycations used inaccurate assay techniques that led to drastic underestimation of the importance of fructose in glycation.