I have to agree with Lisa. No need to wait to test. Even is all you do is a pre-shot test, it lets you make sure the blood sugar level is high enough to give insulin. My vet didn't suggest home testing at all, but if I hadn't been testing at home, I would have lost my sweet boy on day 5. His blood sugar had dropped to 52, and he was on 2 units at that time. If I had just given him the insulin without testing, it would have crashed his blood sugar completely.