Substituted piperazines for treatment of non-insulin dependent diabetes

A compound selected from those of formula (I):

• ##STR32## in which:
• R.sub.1 and R.sub.2, each independently of the other, are selected from hydrogen, alkyl, cycloalkyl, monocyclo-alkylalkyl, dicyclo-alkylalkyl, aryl, and arylalkyl, each of those radicals being optionally substituted,
• R.sub.3 is selected from hydrogen and alkyl,
• n has a value selected from 0, 1 and 2, and
• A represents ##STR33## in which X is selected from oxygen and N-R.sub.4,
• m has a value selected from 1 and 2,
• R.sub.4 is selected from hydrogen and optionally substituted alkyl, alkoxycarbonyl and aryloxycarbonyl, and
• R.sub.5 is selected from hydrogen and alkyl,
• wherein:
• the terms "alkyl", "alkoxy", "monocyclo-alkylalkyl", "dicyclo-alkylalkyl", "arylalkyl" and "alkoxycarbonyl" denote radicals the hydrocarbon chain of which has 1 to 10 carbon atoms inclusive in a straight or branched chain,
• the term "cycloalkyl" denotes a cyclic hydrocarbon radical having 3 to 8 carbon atoms inclusive,
• the terms "aryl", "arylalkyl" and "aryloxycarbonyl" relate to radicals the aromatic part of which is selected from phenyl and naphthyl, and
• the expression "optionally substituted" means that the radicals so described may be substituted by one or more chemical entities selected from alkyl, hydroxy, alkoxy, halogen, haloalkyl, polyhaloalkyl, nitro, amino, alkylamino, and polyalkylamino,
• their stereoisomers, N-oxides, and pharmaceutically-acceptable acid or base addition salts.