My vet advised me to roll it and to inject air in before withdrawing the insulin, those are usual instructions for usual insulin but not for lantus or levemir, they just dont know that, their experience is with animal insulin not the newer human varieties.
Dropping or shaking ect is bad for lantus, I would assume that includes rolling so I didnt do it nor did I add air to the vial, now I am using cartridges its even more important to not add air.