The invention relates to a derivative of a GLP-1 analogue, optionally C-terminally extended, which derivative comprises a first and a second protracting moiety in the form of a C20 or C22 diacid radical, a bis-amino branched linker, and a first and a second further linker each comprising an OEG-like linker element; wherein these elements are interconnected via amide bonds and attached to a Lys residue of the GLP-1 analogue. The invention also relates to intermediate products in the form of novel GLP-1 analogues incorporated in the derivatives of the invention, as well pharmaceutical compositions and medical uses of the derivatives. The derivatives have very long half-lives while maintaining a satisfactory potency, which makes them potentially suitable for once-monthly administration.