The use is described of derivatives of .alpha.-phenylthiocarboxylic and
.alpha.-phenyloxycarboxylic acids with formula (i): in which the
substituents have the meanings described in the text, for the preparation
of a medicine for the prophylaxis and treatment of diabetes, particularly
type 2 diabetes, its complications, the various forms of insulin
resistance, and hyperlipidaemias ##STR00001##