I use Vetsulin for my Petey. Larry is right in that it WAS developed for dogs - which have a slower metabolism that cats and so it runs through the cat's system faster and is harsher than some other insulins. However, every cat is different. It's not a "bad" insulin but there ARE better ( ones that last longer etc). As you saw, Vetsulin is a lot less expensive and we are trying to work on a budget, too. We simply cannot affored even $100 for a 10ml. We pay about $55-60 per 10ml vial of Vetsulin. He gets half a unit twice daily and he has mostly consistent pre-shot numbers between say; 195 and 250. Vetsulin can be successfully used and it will be better than no insulin if you simply cannot afford the more expensive insulin. Another thing that helped a lot was switching Petey to Young Again Zero Carb dry food. He was on 2 units twice a day before we switched. If your sugar cats prefers dry food - this is the one to go with.