If he wants to try it, I would just let him try it to see if it helps him out. If it does, then he feels great & loses weight. If it doesn't, just go back to his other insulin. I would think that your doctor could give him a free sample, like a trial sample so he can test it out. My doctor always gives me free samples of Flonase, thankfully, that stuff is expensive.
Good luck to your husband! ... and you