Abstract: A compound of formula (I): ##STR1## in which: R.sub.1 represents alkyl,R.sub.2, R.sub.4 and R.sub.5, which may be identical or different, represent hydrogen or alkyl,R.sub.3 represents any one of the groups as defined in the description,X represents carbonyl or methylene,Y represents hydrogen or alkyl or aryl,A represents single bond or alkylphenyl,R.sub.6 represents any one of the groups as defined in the description, its isomers as well as its addition salts with a pharmaceutically acceptable acid or base,and medicinal productes containing the same are useful in the treatment of diabetes and complications of diabetic disease.