We has an insulin-dependant cat who lived for eleven years after diagnosis. It got so that the local vets used to send people to us for advice.
We soon discovered that chasing the cat around for urine samples was a complete and utter waste of time. What we did find (through trial and error) was that the most effective way of reducing episodes was to start trickle feeding starting about an hour after his injection. And we also fine-tuned his dosage based on his behaviour.
I also had difficulty at first, inserting the needle, but you do get used to it. He was a bit of a bugger, and developed this trick of tensing his shoulder muscles to make it hard to get a scruff - the actual injections didn't seem to bother him; he just seemed to occasionally rebel.