I tried to use the glucometer but couldn't get any blood from his ears with the needle. He endured it for a time, but when I switched attention to the pawpad he rebelled. SO I left it and decided to ask the vet today to show me how. To answer some of your questions, he was started on 4 units x twice a day. He was not hospitalised and the original vet discouraged me from getting a glucometer. I am using the U40 syringes and I can easily measure 2 units on them.
On Tuesday morning I found him all floppy and unco-ordinated. So I halved the insulin dose and 24 hours later he was back to 'normal', though still more lethargic than his healthy self. I have kept it at 2 units since.
Well, good news. Wellington's glucose is down to either 155 or 108, depending on which machine to believe. But either way, he was 320 last Thursday, so that is a terrific improvement. He has also lost 500 grams in weight, which is good, but much too fast in my opinion for an 8.7 kg cat. Today we went to two vets, the original one, who was pleased with his progress but cross with me when I told her I had changed the insulin dosage and why, and I showed her the charts I had made. She did actually say I had done the right thing, though I should have phoned her and asked. Since it all happened at 7.30 am and there was no-one to ask, and the cat was lying there all floppy, I took things into my own hands. She wants him to go into the clinic for a full day next week, so they can do a curved chart of levels against time of day.
So then I went to my 2nd opinion vet, whom I know through the Association for Cat Rescue. She immediately said he should never have been on such a high dosage at the start of treatment, and also that he was losing weight too fast. And she agreed with me that a wet diet would be better, and we discussed brands and amounts and I think he will be much happier as his daily diet will be increased and be more to his taste.. Then she showed me how to use the glucometer and it turns out I was given the wrong needles. So I think after the curve is done I will transfer all his treatment to the new vet - she is older and into nutrition, and I feel much more trust.