Glycans are the ultimate layer of molecular complexity generated by modifying proteins with chemical structures that integrate genetic, epigenetic, and environmental information. Hundreds of genes are involved in the complex pathway of glycan biosynthesis and glycome composition is significantly heritable as a complex trait. Alternative glycosylation (attaching different glycans to the same glycosylation site on a protein) modulates protein function and in this way actively participates in the transition from health to disease. By analysing over 200,000 individuals, we demonstrated that glycans have significant biomarker potential in personalisation of pharmacological and lifestyle interventions aimed at promoting health and decreasing the risk of disease development.