Frio and other cool solutions
I've traveled with an English product called "Frio." It's a pouch, in various sizes, with a liner containing water absorbent crystals, much like some cooling vests for riders, and bandannas for same.
Insulin stays cool as long as the humidity isn't too high. I've traveled a lot with it, and it works. I know there are American versions too; don't know the name.