A SorCS1-like agent for use in the treatment of insulin resistance and/or a disease associated with insulin resistance in an individual, wherein said agent is selected from the group consisting of: a) an isolated soluble SorCS1 polypeptide selected from the group consisting of i) an amino acid sequence consisting of SEQ ID NOs: 5, 10, 15, 21, 27 and 33; ii) a biologically active sequence variant or naturally occurring allelic variant of the amino acid sequence of i) wherein the variant has at least 70% sequence identity to said SEQ ID NO. 5, 10, 15, 21, 27 or 33; or iii) a biologically active fragment comprising an amino acid sequence selected from the group consisting of: SEQ ID NO: 1 aa 103-124, SEQ ID NO: 1 aa 125-143, SEQ ID NO: 1 aa 144-162, SEQ ID NO: 1 aa 197-218, SEQ ID NO: 1 aa 391-409, SEQ ID NO: 1 aa 661-684, and SEQ ID NO: 1 aa 763-783, SEQ ID NO: 1 aa 859-876, or a variant of said fragment, wherein the variant has at least 70% sequence identity to said SEQ ID NO: 1 aa 103-124, SEQ ID NO: 1 aa 125-143, SEQ ID NO: 1 aa 144-162, SEQ ID NO: 1 aa 197-218, SEQ ID NO: 1 aa 391-409, SEQ ID NO: 1 aa 661-684, and SEQ ID NO: 1 aa 763-783, SEQ ID NO: 1 aa 859-876; wherein said isolated soluble SorCS1 polypeptide is capable of binding to the insulin receptor at a SorCS1 binding site and being capable of sensitizing of an insulin receptor, and wherein the biological activity is sensitization of an insulin receptor, b) a nucleic acid sequence encoding a polypeptide as defined in a); c) an expression vector comprising the nucleic acid molecule as defined in b), d) an isolated host cell transformed or transduced with the nucleic acid of b) or the vector of c). a) an isolated soluble SorCS1 polypeptide selected from the group consisting of i) an amino acid sequence consisting of SEQ ID NOs: 5, 10, 15, 21, 27 and 33; ii) a biologically active sequence variant or naturally occurring allelic variant of the amino acid sequence of i) wherein the variant has at least 70% sequence identity to said SEQ ID NO. 5, 10, 15, 21, 27 or 33; or iii) a biologically active fragment comprising an amino acid sequence selected from the group consisting of: SEQ ID NO: 1 aa 103-124, SEQ ID NO: 1 aa 125-143, SEQ ID NO: 1 aa 144-162, SEQ ID NO: 1 aa 197-218, SEQ ID NO: 1 aa 391-409, SEQ ID NO: 1 aa 661-684, and SEQ ID NO: 1 aa 763-783, SEQ ID NO: 1 aa 859-876, or a variant of said fragment, wherein the variant has at least 70% sequence identity to said SEQ ID NO: 1 aa 103-124, SEQ ID NO: 1 aa 125-143, SEQ ID NO: 1 aa 144-162, SEQ ID NO: 1 aa 197-218, SEQ ID NO: 1 aa 391-409, SEQ ID NO: 1 aa 661-684, and SEQ ID NO: 1 aa 763-783, SEQ ID NO: 1 aa 859-876; wherein said isolated soluble SorCS1 polypeptide is capable of binding to the insulin receptor at a SorCS1 binding site and being capable of sensitizing of an insulin receptor, and wherein the biological activity is sensitization of an insulin receptor, i) an amino acid sequence consisting of SEQ ID NOs: 5, 10, 15, 21, 27 and 33; ii) a biologically active sequence variant or naturally occurring allelic variant of the amino acid sequence of i) wherein the variant has at least 70% sequence identity to said SEQ ID NO. 5, 10, 15, 21, 27 or 33; or iii) a biologically active fragment comprising an amino acid sequence selected from the group consisting of: SEQ ID NO: 1 aa 103-124, SEQ ID NO: 1 aa 125-143, SEQ ID NO: 1 aa 144-162, SEQ ID NO: 1 aa 197-218, SEQ ID NO: 1 aa 391-409, SEQ ID NO: 1 aa 661-684, and SEQ ID NO: 1 aa 763-783, SEQ ID NO: 1 aa 859-876, or a variant of said fragment, wherein the variant has at least 70% sequence identity to said SEQ ID NO: 1 aa 103-124, SEQ ID NO: 1 aa 125-143, SEQ ID NO: 1 aa 144-162, SEQ ID NO: 1 aa 197-218, SEQ ID NO: 1 aa 391-409, SEQ ID NO: 1 aa 661-684, and SEQ ID NO: 1 aa 763-783, SEQ ID NO: 1 aa 859-876; SEQ ID NO: 1 aa 103-124, SEQ ID NO: 1 aa 125-143, SEQ ID NO: 1 aa 144-162, SEQ ID NO: 1 aa 197-218, SEQ ID NO: 1 aa 391-409, SEQ ID NO: 1 aa 661-684, and SEQ ID NO: 1 aa 763-783, SEQ ID NO: 1 aa 859-876, or a variant of said fragment, wherein the variant has at least 70% sequence identity to said SEQ ID NO: 1 aa 103-124, SEQ ID NO: 1 aa 125-143, SEQ ID NO: 1 aa 144-162, SEQ ID NO: 1 aa 197-218, SEQ ID NO: 1 aa 391-409, SEQ ID NO: 1 aa 661-684, and SEQ ID NO: 1 aa 763-783, SEQ ID NO: 1 aa 859-876; b) a nucleic acid sequence encoding a polypeptide as defined in a); c) an expression vector comprising the nucleic acid molecule as defined in b), d) an isolated host cell transformed or transduced with the nucleic acid of b) or the vector of c).