what Wendy said! It's a quick acting insulin that is in and out in about 4 hours, although in cats with iaa it can last longer. R is used in addition to one of L insulins, not instead of them.
If you want to try it, pick up a bottle of either Humulin R or Novolin R (they are the same thing) at your pharmacy. For whatever reason they don't require a prescription. It's relatively cheap - my vial for punkin cost $35 and lasted for his whole life, then I passed it on to someone else. It isn't as delicate as the L insulins. You'll use the same syringes. When you have it, then we can take a look and find a time that one of the experienced R users will be able to stay with you for the following 4 hours. You'll start with a tiny dose, test every hour, then depending on what that does, decide what the next step is.
The goal with using R isn't to replace the L, just to bring down the blood sugar some so the L can do its job.
We can take it one step at a time. Go ahead and get the bottle of R if you want to try this and let me know.