  In this paper the effects of time-dependent Newton constant G during
inflation are studied. We present the formalism of curvature perturbations in
an inflationary system with a time-dependent Newton constant. As an example we
consider a toy model in which G undergoes a sudden change during inflation. By
imposing the appropriate matching conditions the imprints of this sharp change
in G on curvature perturbation power spectrum are studied. We show that if G
increases (decreases) during the transition the amplitude of curvature
perturbations on large scales decreases (increases). In our model with a sudden
change in G a continuous sinusoidal modulations on curvature power spectrum is
induced. However, in a realistic scenario in which the change in G has some
finite time scale we expect these sinusoidal modulations to be damped on short
scales. The generated features may be used to explain the observed glitches on
CMB power spectrum. This puts a bound on $\Delta G$ during inflation of roughly
the same order as current bounds on $\Delta G$ during the entire observed age
of the universe.
