  The Gamma-Ray Large Area Space Telescope (GLAST), scheduled to be launched in
Fall 2007, is a next generation high energy gamma-ray observatory. The Large
Area Telescope (LAT) instrument on-board GLAST with a wide field of view ($>$ 2
sr), large effective area and 20 MeV to $>$300 GeV energy range, will provide
excellent opportunity for future Dark Matter studies. We present an overview of
the GLAST Dark Matter and New Physics Working Group efforts in the study of the
LAT capability to detect a gamma-ray flux coming from WIMP pair annihilations
in diffuse astrophysical sources. Particular attention will be given to
extragalactic diffuse gamma-ray radiation and line searches from annihilation
into gamma-gamma and/or gamma-Z final states.
