  The spectral data on the diffuse Galactic gamma-rays, at medium and high
latitudes (|b| > 10) and energies of 1-100 GeV, recently published by the Fermi
Collaboration are used to produce a novel study on the gamma-ray emissivity in
the Galaxy. We focus on analyzing the properties of propagation of cosmic rays
(CRs), using the publicly available DRAGON code. We critically address some of
the models for the interstellar HI and H2 gas distributions commonly used in
the literature, as well as test a variety of propagation models. Each model
assumes a distinct global profile for the diffusion and the re-acceleration of
CRs. Fitting propagation parameters to well measured local CRs such as, the B/C
ratio, protons, antiprotons and electron, positron fluxes, we evaluate the
gamma-ray spectra at medium and high latitudes in order to place further
constraints on these propagation models.
