No, I am not aware of any people who have contacted us with any kind of resistance to
Lantus. I do know that
Lantus must be replaced at the end of a month on one bottle. The expiration date is really important, for near the end of the month, some of us find that it no longer crystallizes properly. Some people notice that when the Lantus bottle is about one month old, it doesn't work well. But if you just started the bottle, this is probably not the problem.