  We calculate the resistance and shot noise in the edge states of a 2D
topological insulator that result from the exchange of electrons between these
states and conducting puddles in the bulk of the insulator. The two limiting
cases where the energy relaxation is either absent or very strong are
considered. A finite time of spin relaxation in the puddles is introduced
phenomenologically. Depending on this time and on the strength of coupling
between the edge states and the puddles, the Fano factor $F=S_I/2eI$ ranges
from 0 to 1/3, which is in an agreement with the available experimental data.
