  Searches for Dark Matter suggest that it couples to ordinary matter only very
weakly and possibly only through the Higgs or other scalar bosons. On the other
hand, neutrinos might not couple to the Higgs boson directly, but only through
a loop of Dark Matter particles, which would naturally explain the small
neutrino masses. We demonstrate that current experimental constraints on such a
``scotogenic'' scenario allow to make the linear dependence of the lightest
neutrino mass on the dark sector-Higgs coupling explicit, so that a measurement
by the KATRIN experiment would directly determine its value.
