A pharmaceutical composition for the prevention or treatment of diabetes comprising a long-acting insulin conjugate and a long-acting insulinotropic peptide conjugate, wherein each of the long-acting insulin conjugate and the long-acting insulinotropic peptide conjugate is prepared by linking insulin or insulinotropic peptide with an immunoglobulin Fc region via a non-peptidyl linker selected from the group consisting of polyethylene glycol, polypropylene glycol, ethylene glycol-propylene glycol copolymer, polyoxyethylated polyol, polyvinyl alcohol, polysaccharide, dextran, polyvinyl ethyl ether, a biodegradable polymer, a lipid polymer, chitin, hyaluronic acid, and a combination thereof; wherein the insulinotropic peptide is selected from the group consisting of a native exendin-4, an exendin-4 derivative prepared by deleting N-terminal amine group, an exendin-4 derivative prepared by substituting N-terminal amine group with hydroxyl group, an exendin-4 derivative prepared by modifying N-terminal amine group with dimethyl group, an exendin-4 derivative prepared by deleting α-carbon of the first amino acid of exendin-4 (histidine), an exendin-4 variant prepared by substituting 12th amino acid (lysine) of exendin-4 with serine, and an exendin-4 variant prepared by substituting 12th amino acid (lysine) of exendin-4 with arginine; and wherein the insulin is a native insulin; a basal insulin; an insulin derivative which has at least 80% amino acid sequence identity to the native insulin, wherein a chemical group of one or more of the amino acid residues of the native insulin is chemically substituted, deleted, or modified, and wherein the insulin derivative has a function of lowering blood glucose level in a body; or a fragment thereof. wherein each of the long-acting insulin conjugate and the long-acting insulinotropic peptide conjugate is prepared by linking insulin or insulinotropic peptide with an immunoglobulin Fc region via a non-peptidyl linker selected from the group consisting of polyethylene glycol, polypropylene glycol, ethylene glycol-propylene glycol copolymer, polyoxyethylated polyol, polyvinyl alcohol, polysaccharide, dextran, polyvinyl ethyl ether, a biodegradable polymer, a lipid polymer, chitin, hyaluronic acid, and a combination thereof; wherein the insulinotropic peptide is selected from the group consisting of a native exendin-4, an exendin-4 derivative prepared by deleting N-terminal amine group, an exendin-4 derivative prepared by substituting N-terminal amine group with hydroxyl group, an exendin-4 derivative prepared by modifying N-terminal amine group with dimethyl group, an exendin-4 derivative prepared by deleting α-carbon of the first amino acid of exendin-4 (histidine), an exendin-4 variant prepared by substituting 12th amino acid (lysine) of exendin-4 with serine, and an exendin-4 variant prepared by substituting 12th amino acid (lysine) of exendin-4 with arginine; and wherein the insulin is a native insulin; a basal insulin; an insulin derivative which has at least 80% amino acid sequence identity to the native insulin, wherein a chemical group of one or more of the amino acid residues of the native insulin is chemically substituted, deleted, or modified, and wherein the insulin derivative has a function of lowering blood glucose level in a body; or a fragment thereof.