Disclosed is a use of a pharmaceutical composition comprising or made from a DPP-4 inhibitor which is 1-[(4-methyl-quinazolin-2-yl)methyl]-3-methyl-7-(2-butyn-1-yl)-8-(3-(R)-amino-piperidin-1-yl)-xanthine, and metformin； a stabilizer which is a nucleophilc and/or basic agent, a buffering agent or a pH modifying agent which is L-arginine, and one or more pharmaceutical excipients； for preparing a medicament for use in treating and/or preventing (including slowing the progression and/or delaying the onset) of metabolic diseases, especially type 2 diabetes mellitus and conditions related thereto (e.g. diabetic complications), either in type 2 diabetes patients who have not been previously treated with an antihyperglycemic agent, or in type 2 diabetes patients with insufficient glycemic control despite therapy with one or two conventional antihyperglycemic agents selected from metformin, sulphonylureas, thiazolidinediones (e.g. pioglitazone), glinides, alpha-glucosidase blockers, GLP-1 or GLP-1 analogues, and insulin or insulin analogues； optionally in combination with one or more other active substances.
