Disclosed are compounds of formula (I) or a pharmaceutically acceptable salt thereof, which have an excellent blood glucose-lowering effect and protective effect on beta cells or the pancreas. Examples of such compounds are； 4-(5-{ (1R)-1-[4-(cyclopropylcarbonyl)phenoxy]propyl} -1,2,4-oxadiazol-3-yl)-N-[(2S)-2,3-dihydroxypropyl]-2-fluorobenzamide and 4-(5-{ (1R)-1-[4-(2,2-Dimethylpropanoyl)phenoxy]propyl} -1,2,4-oxadiazol-3-yl)-2-fluoro-N-[2-hydroxy-1-(hydroxymethyl)ethyl]benzamide. Also disclosed is a pharmaceutical composition having an excellent therapeutic and/or prophylactic effect against type 1 diabetes mellitus, type 2 diabetes mellitus, and other such diseases in which blood glucose rises in response to sugar metabolism anomalies.
