m not a medical professional, just the parent of a kid
with diabetes. So have you already switched to
Lantus and are seeing the gain? That isn't clear, but I presume that's the case.
Yes, switching insulins can cause weight gain, as the body reacts differently to different insulins. Insulins can stimulate the body into causing fat production, and when the body has to learn to deal with a new insulin, it may very well react that way.