This invention relates to a compound having an exceptional blood-sugar-reducing effect or a pharmaceutically acceptable salt thereof, and more particularly to a compound represented by the formula (I) or a pharmaceutically acceptable salt thereof, wherein X is =C(R8)-, -CH(R8)-, =N-, or -O-； Y is =C(R9)-, -CH(R9)-, or =N-； Z is =C(R10)-, -CH(R9)-, or =N-； R1 is H, a substitutable C1-3 alkyl, a substitutable C1-3 alkoxy, a substitutable C2-3 alkenyl, a substitutable C3-6 cycloalkyl, a C1-3 alkoxycarbonyl, a substitutable aminocarbonyl, a heterocyclic carbonyl, a carboxy, or a halogen； R2 is the same or different and is H, a C1-3 alkyl, a C3-6 cycloalkyl, a C1-3 alkoxy, a carboxy, or a halogen； R3 is H, a substitutable C1-3 alkyl, a C3-6 cycloalkyl, a substitutable C1-3 alkoxy, or carboxy； R4 and R5 are the same as or different from the C1-3 alkyl or are bonded to form a 3-6 membered saturated carbon ring； R6 and R7 are the same as or different from the C1-3 alkyl or are bonded to form a 3-6 membered saturated carbon ring； R8 is H or a substitutable C1-3 alkyl； R9 is H, a substitutable C1-3 alkyl, a C1-3 alkoxycarbonyl, a carboxy, or a carboxy-substituted C2-3 alkenyl； R10 is H, a C1-3 alkoxy, a substitutable C1-3 alkyl, a C6-10 aryl, a heterocyclic ring, a C1-3 alkoxycarbonyl, a substitutable aminocarbonyl, a carboxy-substituted C2-3 alkenyl, or a carboxy； n is 0-1； m is 0-1； and t is 1-2.本發明係關於具有優異之血糖降低作用的化合物或其藥理上容許鹽。一種以下述通式(I)所表示之化合物或其藥理上容許鹽，[式中，X為=C(-R8)-、-CH(-R8)-、=N-、-O-；Y為=C(-R9)-、-CH(-R9)-、=N-；Z：=C(-R10)-、-CH(-R9)-、=N-；R1為氫原子、可取代之C1-C3烷基、可取代之C1-C3烷氧基、可取代之C2-C3烯基、可取代之C3-C6環烷基、C1-C3烷氧羰基、可取代之胺基羰基氮、雜環羰基、羧基、鹵素原子；R2為相同或相異，氫原子、C1-C3烷基、C3-C6環烷基、C1-C3烷氧基、羧基、鹵素原子；R3為氫原子、可取代之C1-C3烷基、C3-C6環烷基、可取代之C1-C3烷氧基、羧基；R4及R5為相同或相異C1-C3烷基、或R4及R5鍵結而形成3-6員飽和碳環；R6及R7為相同或相異C1-C3烷基、或R6及R7鍵結而形成3-6員飽和碳環；R8為氫原子、可取代之C1-C3烷基；R9為氫原子、可取代之C1-C3烷基、C1-C3烷氧羰基、羧基、經羧基取代之C2-C3烯基；R10為氫原子、C1-C3烷氧基、可取代之C1-C3烷基、C6-C10芳基、雜環基、C1-C3烷氧羰基、可取代之胺基羰基、經羧基取代之C2-C3烯基、羧基；n為0~1；m為0~1；t為1~2]。
