Just to add my own two cents worth in here. Home testing when using a powerful hormone such as insulin is definitely necessary. Some kitties can go along very nicely with no problems then out of the blue they can hit a hypo number. Without testing on a regular basis there is no way to know if/when that will happen.
I am using Levemir which is a much gentler, slower acting insulin than Caninsulin/Vetsulin. My Maxie is my second FD kitty and was diagnosed less than 2 months ago, but I have a fair deal of experience from treating her brother Tuxie for the last 17 months (he has other health concerns and will never be properly regulated)
I use the AT2 pet meter which reads higher than a human meter. Just three days ago Maxie started off with a preshot of 21.6 ( 367 US) At +3 she was 46 ( 83 US) and I started giving HC because of how fast she was dropping. She continued dropping and I continued giving HC food and syrup. She ended up with a low of 1.8 ( 32 US) at +6 . I was finally able to bring her numbers up, but if I had not been able to I was preparing to take her to the ER. Never once did she display any unusual behaviour that would have alerted me to the low numbers. If I had not been testing and able to bring the numbers up at home, there is a strong possibility she could have dropped even further and it could have become a critical situation.
A critical hypo event can cause brain damage or worse:
"
Hypoglycemia is what every diabetic fears -- very low
blood glucose. Since the brain requires glucose for fuel at every second, it's possible to induce coma, seizures,brain damage
[1][2][3] and death by letting blood glucose drop too low. Because the brain is almost totally dependent on glucose to make use of oxygen
[4], it is somewhat like having severe breathing problems. Though the causes and mechanisms are different, in both cases the brain does not have enough oxygen, and similar symptoms and problems can occur. It is caused by giving too much insulin for the body's current needs."
http://petdiabetes.wikia.com/wiki/Hypoglycemiai
The members on here who strongly encourage home-testing have seen cases where a kitty has ended up in the ER for several days at a very expensive cost and unfortunately there have been some that even with critical ER care the kitty has died. Believe me if I could just give shots twice a day and not have to worry, I certainly would not be so adamant about home-testing, but the realities of not home testing can be very harsh. No one on here is trying to scare anyone, only to give them the proper tools to do the best possible for their kitties. Everyone here cares about all the member's kitties...each and every one.