I have had both a diabetic dog and a diabetic cat.
The diabetic dog, Maia, lived for four years with the condition, and was blind as well. She had a stroke or heart attack at age 14 (legs were paralyzed). We gave her insulin every day, which is not difficult to do, providing that the pet doesn't resist, which Maia didn't. However it was sometimes difficult to regulate her, and there were many times when we thought she was down for the count. She had blood sugar crashes on occasion, which were scary. The solution to that is to get some sugar into the pet immediately - we used syrup.
Maia was a total trooper of a dog! Unfortunately it was more difficult with the diabetic cat, and he didn't live more than six months after diagnosis. It was very hard to give him the shot, as he didn't like it and wouldn't stand still. And a cat might not be as willing as a dog to eat up a bowl of syrup in the case of a blood sugar crash.
I did know someone with a cat who lived for a number of years with diabetes. I don't remember all the details, but do recall that for some reason the women who owned the cat was spending hundreds of dollars at the vet some months.
I relied heavily on a website forum called Pets with Diabetes when caring for Maia. It was literally a life-saver, as there was a time when she wasn't responding to the insulin and just kept getting sicker and thinner. It was a person on the board who suggested we might be using a needle that was calibrated differently from the one the vet used. This turned out to be the case, as we'd got some needles from a person with diabetes. We adjusted the insulin, and Maia started to get better immediately. Even the vet had not considered that calibration might be the issue.
I looked for that website, and didn't get a hit.
But there are lots of resources on the web for dealing with a diabetic pet, and I'm sure there are forums about it, as it is a scary, intimidating situation and people living with it need a lot of support and advise.
Good luck Aussie Willie - there is hope.