Glycosylated GLP-1 peptide

1. An oligosaccharide chain added GLP-1 peptide having GLP-1 activity, wherein at least two amino acids are each substituted with an oligosaccharide chain added amino acid, wherein the GLP-1 peptide is:

(a) GLP-1; or

(b) a peptide having the amino acid sequence of GLP-1 with deletion, substitution or addition of 1-3 amino acids,

wherein each of the substituted sites is selected from the group consisting of the positions 18, 20, 22, 26, 30, 34, and 36 of GLP-1,

and

wherein each of said oligosaccharide chains is independently a biantennary complex-type oligosaccharide chain and represented by the following formula:

wherein

R 1 and R 2 are the same or different and each represents

and Ac represents an acetyl group;

or a pharmaceutically acceptable salt thereof.

2. The oligosaccharide chain added GLP-1 peptide according to claim 1 , wherein each of said oligosaccharide chain added amino acids is independently oligosaccharide chain added Asn and/or oligosaccharide chain added Cys.

3. The oligosaccharide chain added GLP-1 peptide according to claim 1 , wherein in said oligosaccharide chain added amino acid, the oligosaccharide chain is linked to the amino acid without a linker.

4. The oligosaccharide chain added GLP-1 peptide according to claim 1 , wherein said oligosaccharide chain is substantially uniform.

5. The oligosaccharide chain added GLP-1 peptide according to to claim 1 , wherein:

each of said oligosaccharide chain added amino acids is oligosaccharide chain added Asn;

in said oligosaccharide chain added amino acid, the oligosaccharide chain is linked to the amino acid without a linker;

said oligosaccharide chains each consist of four or more sugars;

and

said oligosaccharide chain is substantially uniform.

6. The oligosaccharide chain added GLP-1 peptide according to claim 1 , having at least one of the following properties:

a higher stability in blood than that of GLP-1;

an activity of controlling blood-sugar levels at least 10 times that of GLP-1 in OGTT (Oral Glucose Tolerance Test); and

DPP-IV resistance at least 30 times that of GLP-1.

7. A pharmaceutical composition comprising the oligosaccharide chain added GLP-1 peptide according to claim 1 as an active ingredient.

8. The pharmaceutical composition according to claim 7 for treating or preventing disease associated with GLP-1.

9. The pharmaceutical composition according to claim 8 , wherein said disease associated with GLP-1 is diabetes.

10. A method for treating or preventing disease associated with GLP-1 comprising administering effective amount of the oligosaccharide chain added GLP-1 peptide according to claim 1 .

11. An oligosaccharide chain added GLP-1 peptide having GLP-1 activity according to claim 1 , wherein, in said oligosaccharide chain added amino acid, the oligosaccharide chain is linked to the amino acid via a linker, and said linker contains an amino acid at the terminal bound to said oligosaccharide chain.

12. The oligosaccharide chain added GLP-1 peptide according to claim 11 , the amino acid bound to said linker is Lys.

13. The oligosaccharide chain added GLP-1 peptide according to claim 11 , wherein the amino acid contained in said linker is Asn.

14. The oligosaccharide chain added GLP-1 peptide according to claim 11 , wherein the oligosaccharide chain is substantially uniform.

15. A pharmaceutical composition comprising the oligosaccharide chain added GLP-1 peptide according to claim 11 as an active ingredient.