D-galactose has been used extensively as an ultrasound contrast agent, and recently as therapy for the cardiac variant of Fabry’s disease. D-galactose treat the patients with certain types of congenital disorders of glycosylation (CDG). D-galactose increases nucleotide sugar pools in patients parallel with improved LLO synthesis, improved galactosylation and sialylation. D-galactose might have beneficiary effect in other types of glycosylation.