Disclosed is a pharmaceutical composition comprising a combination of (A) (1S)-1,5-anhydro-1-[5-(4-ethoxybenzyl)-2-methoxy-4-methylphenyl]-1-thio-D-glucitol (Luseogliflozin / TS-071) or a pharmaceutically acceptable salt thereof or a hydrate of the compound or the salt and (B) sitagliptin. Also disclosed is the use of a combination as defined above in the manufacture of a medicament for preventing or treating diabetes mellitus, diseases associated with diabetes mellitus, or complications of diabetes mellitus, wherein (A) and (B) are formulated for simultaneous or separate administration, wherein the prevention or treatment of diabetes mellitus preferably includes one or more of the prevention or treatment of type 2 diabetes, diabetic retinopathy, diabetic nephropathy, diabetic neuropathy, cerebrovascular disorder, ischemic cardiac disease, or peripheral arterial disease.
