Pharmaceutical formulations and pharmaceutical compositions comprising reverse PEGylated oxyntomodulin conjugates, and methods of producing, and using the same are described. Conjugates include those attaching a polyethylene glycol polymer (PEG polymer) and 9-fluorenylmethoxycarbonyl (Fmoc) or 2-sulfo-9-fluorenylmethoxycarbonyl (FMS) to a oxyntomodulin peptide, wherein the PEG polymer is attached to the amino terminus or to an amino residue within the oxyntomodulin via a flexible linker, wherein the flexible linker comprises a Fmoc or a FMS.
