The invention discloses a medicinal composition for treating type 2 diabetes of mammals including human beings, particularly a medicinal composition prepared by mixing (R)-7-[3-amino-4-(2,4,5-trifluoro-phenyl)-butyryl]-3-trifluoromethyl-5,6,7,8,-tetrahydro-imidazo[1,5-a]-carboxylic methyl ether or pharmaceutically acceptable salt thereof and rosiglitazone or pioglitazone or pharmaceutically acceptable salts of the rosiglitazone or pioglitazone in fixed dose ratio, a method for preparing the medicinal composition, and application of the medicinal composition to treating type 2 diabetes in mammals including human beings.
