In supersymmetric models with Dirac neutrinos, the lightest sneutrino
can be an excellent thermal dark matter candidate when the soft
sneutrino A-parameter is large. We focus on scenarios where the mass
of the mixed sneutrino is of the order of GeV, and discuss
phenomenological constraints on the parameter space. We show that the
allowed regions can be explored by measuring Higgs boson properties at
future collider experiments.