Exendins or exendin analogs modified by one or more PEG derivatives that may be linked to one or more amino acids of the exendins or exendin analogs are provided. The PEG derivatives may have branched structure set forth in any one of formulas I-IV. Compositions including the PEG derivative modified exendin or exendin analog, methods of making or administering the modified exendin or exendin analog, and various uses thereof are also provided.
