Hi,
I have not used lantus, but I do use
levemir. Both are medium acting basal insulins.
Levemir works best injected twice a day. I inject just before going to bed (22 units), and when I wake up in the morning (8 units). As you can see, I don't use the same dose morning and evening, as I find I need more basal insulin at night when I am inactive, than during the day when I am active.
You will need to adjust your dosage based on your target blood sugar levels.