Method for prevention and treatment of metabolic syndrome through the inhibition of psgl-1

Disclosed is a prophylactic and/or therapeutic agent which can exhibit an effect by itself on the prevention and/or treatment of a basic condition of a lifestyle-related disease such as metabolic syndrome and type-2 diabetes.  Also disclosed is a method for the screening of the prophylactic and/or therapeutic agent. Specifically disclosed is a prophylactic and/or therapeutic agent for metabolic diseases, which comprises an inhibitor of PSGL-1 as an active ingredient.