A composition, in aqueous solution, comprising insulin in hexameric form, at least one substituted anionic compound and at least one polyanionic compound, said substituted anionic compound consisting of a discrete number n of between 1 and 8 of identical or different saccharide units, linked via identical or different glycoside bonds, said saccharide unit or one of said saccharide units being in open, oxidized or reduced form, said compound comprising salifiable carboxyl groups and said substituted anionic compound bearing on its reductive chain end at least one radical AA resulting from an aromatic amino acid comprising a phenyl or an indole, which may or may not be substituted, or an aromatic amino acid derivative comprising a phenyl or an indole, which may or may not be substituted.
