A method for the measurement of autoantibodies to IRF members as serological markers comprising detecting in a sample to be investigated the presence and/or the binding properties of analyte antibodies reactive with one or more antigenic molecules, said method comprising: (a) providing one or more first antigenic molecules with which analyte antibodies when present in said sample can interact and which first antigenic molecule is selected from the insulin receptor family; and (b) providing one or more second antigenic molecules with which analyte antibodies when present in said sample can interact and which second antigenic molecule is selected from the IRF; and (c) contacting said first antigenic molecules as provided by step (a) and said second antigenic molecules as provided by step (b) simultaneously or successively with the sample to be investigated, whereby analyte antibodies when present in said sample can interact with said antigenic molecules so as to form complexes comprising [first antigenic molecule]-[analyte antibody]-[second antigenic molecule]; and (d) prior to, or concurrent with, or subsequent to, step (c), providing immobilizing means whereby said first antigenic molecule as present in the said complexes formed in step (c), respectively, as capable to form complexes in step (c) is immobilized to a solid support prior to, or concurrent with, or subsequent to, step (c); and (e) prior to, or concurrent with, or subsequent to, step (c), providing first labeling means whereby said second antigenic molecule as present in the said complexes formed in step (c), respectively, as capable to form complexes in step (c) is labeled with said first labeling means prior to, or concurrent with, or subsequent to, step (c); and (g) detecting the presence of said complexes formed in or subsequent to step (c) so as to provide indication of analyte antibodies present in said sample. (a) providing one or more first antigenic molecules with which analyte antibodies when present in said sample can interact and which first antigenic molecule is selected from the insulin receptor family; and (b) providing one or more second antigenic molecules with which analyte antibodies when present in said sample can interact and which second antigenic molecule is selected from the IRF; and (c) contacting said first antigenic molecules as provided by step (a) and said second antigenic molecules as provided by step (b) simultaneously or successively with the sample to be investigated, whereby analyte antibodies when present in said sample can interact with said antigenic molecules so as to form complexes comprising [first antigenic molecule]-[analyte antibody]-[second antigenic molecule]; and (d) prior to, or concurrent with, or subsequent to, step (c), providing immobilizing means whereby said first antigenic molecule as present in the said complexes formed in step (c), respectively, as capable to form complexes in step (c) is immobilized to a solid support prior to, or concurrent with, or subsequent to, step (c); and (e) prior to, or concurrent with, or subsequent to, step (c), providing first labeling means whereby said second antigenic molecule as present in the said complexes formed in step (c), respectively, as capable to form complexes in step (c) is labeled with said first labeling means prior to, or concurrent with, or subsequent to, step (c); and (g) detecting the presence of said complexes formed in or subsequent to step (c) so as to provide indication of analyte antibodies present in said sample.