Benzoic acid derivatives of the formula ##STR1## wherein T is hydrogen or halogen, W is a carboxyl group, an ester or salt thereof; X is ##STR2## wherein R.sub.1 is alkyl having from 2 to 8 carbon atoms, aralkyl or phenyl, cycloalkyl, cycloalkylalkyl or alkylcycloalkyl; R.sub.2 is hydrogen or halogen, R.sub.3 is alkyl having from 5 to 8 carbon atoms, aralkyl or phenyl, or cycloalkyl having from 5 to 8 carbon atoms; R.sub.4 is hydrogen or alkyl; Y is a single chemical bond or a hydrocarbon chain having from 1 to 3 carbon atoms; and Z is hydrogen, halogen, alkyl, alkoxy, alkoxyalkoxy or alkenyloxy, have a blood sugar lowering effect and can be used for the treatment of Diabetes mellitus.