Oligosaccharide chain added GLP-1 peptides are more stable in blood and more active in controlling blood-sugar levels than GLP-1 peptides without added oligosaccharides. Oligosaccharide chain added GLP-1 peptides having GLP-1 activity include at least one or at least two amino acids each substituted with an oligosaccharide chain added amino acid in GLP-1； a peptide having the amino acid sequence of GLP-1 with deletion, substitution or addition of one or several amino acids； or a GLP-1 analog. Oligosaccharide chain added GLP-1 peptides with at least one amino acid substituted with an oligosaccharide chain added amino acid include an oligosaccharide chain with oligo hyaluronic acid. Oligosaccharide chain added amino acids include oligosaccharide chains attached to amino acids via linkers.
