  We present a scenario where neutrino masses and Dark Matter are related due
to a global $U(1)_{B-L}$ symmetry. Specifically we consider neutrino mass
generation via the Zee--Babu two-loop mechanism, augmented by a scalar singlet
whose VEV breaks the global $U(1)_{B-L}$ symmetry. In order to obtain a Dark
Matter candidate we introduce two Standard Model singlet fermions. They form a
Dirac particle and are stable because of a remnant $Z_2$ symmetry. Hence, in
this model the stability of Dark Matter follows from the global $U(1)_{B-L}$
symmetry. We discuss the Dark Matter phenomenology of the model, and compare it
to similar models based on gauged $U(1)_{B-L}$. We argue that in contrast to
the gauged versions, the model based on the global symmetry does not suffer
from severe constraints from $Z'$ searches.
