A21, B30, modified insulin derivatives having an altered action profile

New insulin derivatives of the formula II with an iso-electric point between 5 and 8.5, with improved stability in weakly acid aqueous medium and with a special action profile, and the physiologically tolerated salts of these insulin derivatives, for the treatment of diabetes mellitus; formula II is: in which R1 denotes H or H-Phe, R2 denotes a genetically encodable L-amino acid which contains no amide group, R30 represents the residue of a neutral genetically encodable L-amino acid, R31 represents a physiologically acceptable organic group which is basic in nature and has up to 50 carbon atoms, in whose structure 0 to 3 alpha -amino acids are involved and whose terminal carboxyl group which is present where appropriate can be free, in the form of an ester functionality, an amide functionality, a lactone or reduced to CH20H, and X represents a genetically encodable L-amino acid.