The invention relates to derivatives of GLP-1 like peptides which are C-terminally extended analogs of native GLP-1. The derivatives comprise two side chains, one at a position corresponding to position 42, and one at a position corresponding to position 18, 23, 27, 31, 36, or 38, wherein both positions are when compared to GLP-1(7-37). The side chains comprise a C19, C20, or C22 diacid protracting moiety and optionally a linker. The invention also relates to intermediate products in the form of novel GLP-1 analogs incorporated in the derivatives of the invention, as well as 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.