Hi Claudia.
Generally, we suggest lowering the dose of Lantus (most people here switch from Lantus to Lev) by 30% when switching to Lev. You're dropping the dose by 40% so it should be fine. I'm going to presume the same will hold for switching from ProZinc. You may need to bring the dose up after a few days. It will take 5 - 7 days for a Lev shed to develop and for you to really see any effects from the switch. Just be patient. The other big factor to remember is that Lev dosing is based on the nadir, not on the pre-shot values. It's going to require that you change the way you think about dosing.