Biological activities occurring within cells are regulated by the expression of proteins such as enzymes and translational modifications represented by phosphorylation and glycosylation. Therefore, comprehensive analysis of metabolic products such as sugars, lipids, and amino acids leads to direct and comprehensive observation of life phenomena. As metabolites of glycosylation, not only monosaccharides, oligosaccharides, and phosphosugars which have been already registered in the Human Metabolome Database ( https://hmdb.ca/ ) but also free glycans can be considered as broad-sense sugar metabolic products. If there is a deficiency in lysosomal enzymes related to glycosylation metabolism, lysosomal disease develops. Large amounts of free glycans are observed in the cells and urine of patients with lysosomal disease [1].