A derivative of a GLP-1 peptide, wherein the GLP-1 peptide is of formula I: Formula I: Xaa 7 -Xaa 8 -Glu-Gly-Thr-Xaa 12 -Thr-Ser-Asp-Xaa 16 -Ser-Xaa 18 -Xaa 19 -Xaa 20 -Glu-Xaa 22 -Xaa 23 -Ala-Xaa 25 -Xaa 26 Xaa 27 -Phe-Ile-Xaa 30 -Xaa 31 -Leu-Xaa 33 -Xaa 34 -Xaa 35 -Xaa 36 -Xaa 37 -Xaa 38 -Xaa 39 -Xaa 40 -Xaa 41 -Xaa 42 -Xaa 43, wherein Xaa 7 is L-histidine, -2-Hydroxy-3-(1H-imidazol-4-yl)-propionic acid, D-histidine, desamino-histidine, homohistidine, N α -acetyl-histidine, N α -formyl-histidine, α-methyl-histidine, 3-pyridylalanine, 2-pyridylalanine, or 4-pyridylalanine; Xaa 8 is Ala, Gly, Ser, Aib, (1-aminocyclopropyl) carboxylic acid, or(1-aminocyclobutyl) carboxylic acid; Xaa 12 is Phe or Leu; Xaa 16 is Val or Leu; Xaa 18 is Ser, Val, Lys, Arg, or Leu; Xaa 19 is Tyr or Gln; Xaa 20 is Leu or Met; Xaa 22 is Gly or Glu; Xaa 23 is Gln, Glu, or Arg; Xaa 25 is Ala or Val; Xaa 26 is Arg or Lys; Xaa 27 is Glu, Lys, or Leu; Xaa 30 is Ala, Glu, or Arg; Xaa 31 is Trp or His; Xaa 33 is Val, Lys, or Arg; Xaa 34 is Arg, Lys, His, Asn, or Gin; Xaa 35 is Gly or Ala; Xaa 36 is Arg or Gly; Xaa 37 is Gly, Pro, or Lys; Xaa 38 is Ser, Gly, Ala, Glu, Pro, Lys, or absent; Xaa 39 is Ser, Gly, Ala, Glu, Pro, Lys, or absent; Xaa 40 is Ser, Gly, Ala, Glu, Pro, Lys, or absent; Xaa 41 is Ser, Gly, Ala, Glu, Pro, Lys, or absent; Xaa 42 is Ser, Gly, Ala, Glu, Pro, Lys, or absent; and Xaa 43 is Ser, Gly, Ala, Glu, Pro, Lys, or absent; which GLP-1 peptide comprises a Lys residue at a position corresponding to position 27, 37, 38, 39, 40, 41, 42, or 43 of GLP-1 (SEQ ID NO: 1); which derivative comprises a first and a second protracting moiety selected from Chem. 1 and Chem. 1 a: Chem. 1: HOOC-(CH 2) 18 -CO-*, and Chem. 1 a: HOOC-(CH 2) 20 -CO-*; a branched linker of formula Chem. 2: wherein R 1 is -(CH 2) q -NH-*, wherein q is an integer in the range of 0-5, R 2 is -(CH 2) w -NH-*, wherein w is an integer in the range of 0-5, with the provisos that when w is 0 q is an integer in the range of 1-5, and when q is 0 w is an integer in the range of 1-5; and a first and a second further linker, each comprising an element_1 of formula Chem. 3: wherein k is an integer in the range of 1-15, and n is an integer in the range of 1-5; wherein the first protracting moiety is attached at its *-CO end to a first *-NH end of the branched linker, via the first further linker, the second protracting moiety is attached at its *-CO end to a second *-NH end of the branched linker, via the second further linker; and the branched linker is attached at its *-CO end to the epsilon amino group of the Lys residue of the GLP-1 peptide; or a pharmaceutically acceptable salt, amide, or ester thereof. Xaa 7 is L-histidine, -2-Hydroxy-3-(1H-imidazol-4-yl)-propionic acid, D-histidine, desamino-histidine, homohistidine, N α -acetyl-histidine, N α -formyl-histidine, α-methyl-histidine, 3-pyridylalanine, 2-pyridylalanine, or 4-pyridylalanine; Xaa 8 is Ala, Gly, Ser, Aib, (1-aminocyclopropyl) carboxylic acid, or(1-aminocyclobutyl) carboxylic acid; Xaa 12 is Phe or Leu; Xaa 16 is Val or Leu; Xaa 18 is Ser, Val, Lys, Arg, or Leu; Xaa 19 is Tyr or Gln; Xaa 20 is Leu or Met; Xaa 22 is Gly or Glu; Xaa 23 is Gln, Glu, or Arg; Xaa 25 is Ala or Val; Xaa 26 is Arg or Lys; Xaa 27 is Glu, Lys, or Leu; Xaa 30 is Ala, Glu, or Arg; Xaa 31 is Trp or His; Xaa 33 is Val, Lys, or Arg; Xaa 34 is Arg, Lys, His, Asn, or Gin; Xaa 35 is Gly or Ala; Xaa 36 is Arg or Gly; Xaa 37 is Gly, Pro, or Lys; Xaa 38 is Ser, Gly, Ala, Glu, Pro, Lys, or absent; Xaa 39 is Ser, Gly, Ala, Glu, Pro, Lys, or absent; Xaa 40 is Ser, Gly, Ala, Glu, Pro, Lys, or absent; Xaa 41 is Ser, Gly, Ala, Glu, Pro, Lys, or absent; Xaa 42 is Ser, Gly, Ala, Glu, Pro, Lys, or absent; and Xaa 43 is Ser, Gly, Ala, Glu, Pro, Lys, or absent; R 1 is -(CH 2) q -NH-*, wherein q is an integer in the range of 0-5, R 2 is -(CH 2) w -NH-*, wherein w is an integer in the range of 0-5, with the provisos that when w is 0 q is an integer in the range of 1-5, and when q is 0 w is an integer in the range of 1-5; and a first and a second further linker, each comprising an element_1 of formula Chem. 3: wherein k is an integer in the range of 1-15, and n is an integer in the range of 1-5; wherein the first protracting moiety is attached at its *-CO end to a first *-NH end of the branched linker, via the first further linker, the second protracting moiety is attached at its *-CO end to a second *-NH end of the branched linker, via the second further linker; and the branched linker is attached at its *-CO end to the epsilon amino group of the Lys residue of the GLP-1 peptide; or a pharmaceutically acceptable salt, amide, or ester thereof. wherein k is an integer in the range of 1-15, and n is an integer in the range of 1-5; wherein the first protracting moiety is attached at its *-CO end to a first *-NH end of the branched linker, via the first further linker, the second protracting moiety is attached at its *-CO end to a second *-NH end of the branched linker, via the second further linker; and the branched linker is attached at its *-CO end to the epsilon amino group of the Lys residue of the GLP-1 peptide;