The present invention relates to compounds, which are useful for treatment and/or prevention of diabetes mellitus, diabetes mellitus complications or obesity, since the compounds have glucokinase-activating effects, and are presented in Formula (I): wherein R1 represents a lower alkylsulfonyl group； R2 represents a hydrogen atom； R20 represents, e.g., a hydrogen atom； m represents an integer of from 1 to 3； and n represents zero or 1, or relates to a pharmaceutically acceptable salts thereof.
