Peptides with an insulin-like action, of formula I: ##STR1## in which G is a hydrogen atom, an amino add residue, or a monosubstituted or polysubstituted amino acid; D is an amino acid residue, a phosphoamino acid residue, a monosaccharide residue, or a covalent bond; E is --NH--(CH.sub.2).sub.n --NR.sup.5.sub.2, a glycerol residue, or --NH--(CH.sub.2).sub.p --R.sup.6 --R.sup.7 ; R.sup.1 is (C.sub.1 -C.sub.4)-alkyl or .dbd.O; R.sup.2 is a sulfhydryl protecting group, (C.sub.1 -C.sub.3)-alkyl, or a hydrogen atom; R.sup.3 and R.sup.4, independently of one another, are a hydrogen atom or methyl; R.sup.5, each being identical or different, is a hydrogen atom, 1 to 6 monosaccharide residues, or 1 to 6 monosubstituted or polysubstituted monosaccharide residues; R.sup.6 is O PO.sub.4 H, PO.sub.2 H, NHCOO, S or OCOO; R.sup.7 is a hydrogen atom, 1 to 6 monosaccharide residues, or 1 to 6 monosubstituted or polysubstituted monosaccharide residues; w is an integer 1 or 2; their preparation and use for treatment of diabetes mellitus or insulin-independent diabetes.