Provided are a marker capable of detecting insulin resistance and diabetes in a blood sample, a method for analyzing said marker, and a method for screening for a substance that improves insulin resistance and improves or suppresses diabetes. Specifically disclosed are a blood insulin resistance marker and a marker for diabetes in blood, which include a polypeptide comprising at least 15 consecutive amino acids in an amino acid sequence constituting progranulin. Also specifically disclosed is a method for analyzing a blood marker which includes: a step for measuring the concentration of the insulin resistance marker or the diabetes marker in the blood sample and a step for comparing the measured concentration and the normal blood concentration for the marker. Also specifically disclosed is a method for screening for a substance that improves insulin resistance and improves or suppresses diabetes, which includes: a step for administering a candidate substance into a living body that exhibits insulin resistance or has contracted diabetes and measuring the concentration of the marker in the blood of the living body after administration and a step for comparing the measured concentration and the concentration of the marker in the blood of a living body to which said substance was not administered.Cette invention concerne un marqueur capable de détecter la résistance à linsuline et le diabète dans un échantillon sanguin, un procédé pour analyser ledit marqueur, et un procédé de criblage pour identifier une substance capable daméliorer la résistance à linsuline et daméliorer, voire de supprimer, le diabète. Plus spécifiquement, cette invention concerne un marqueur sanguin de résistance à linsuline et un marqueur du diabète dans le sang, qui comprennent un polypeptide comprenant au moins 15 acides aminés consécutifs dune séquence dacides aminés constituant la progranuline. Un procédé danalyse dun marqueur sanguin est également décrit, ledit procédé comprenant : une étape c
