Short answer, yes.
Long answer:
If you are using prefilled carts it will be hard to dilute them simply by dropping some glycerin on them. You will have glycerin on the top and your e-juice below. If this is the case I would get a bottle of juice, rinse your cart filler, and refill them yourself. But, if you are buying juice, you can already lower the strength by buying a lower nic strength.
If you have juice and are trying to dilute it, then glycerin will be fine. It is a lot thicker than PG so you will have to mess with it a bit to get the proper consistency.