The present invention relates to the use of a substituted 2-phenylbenzimidazole of formula I ##STR00001## wherein R.sup.1, R.sup.2, R.sup.3, R.sup.4, R.sup.5 and m have the meanings given in the claims, for the preparation of a medicament for the treatment or prevention of diseases involving glucagon receptors, as well as new compounds of formula I wherein R.sup.1 is a group of formula ##STR00002##