Welcome!
It's a good thing Kit Kat likes canned wet food, because food plays a very important role in regulating our diabetic cats. Janet & Binky's food chart is here
http://www.felinediabetes.com/diabetic-cat-diets.htm and you will see a number of brands (Friskies, Fancy Feast, etc.), and alot of varieties that are low carb - diabetic kitty's need a low carb wet food diet. You do NOT have to purchase the food at the vet's office - not only is it not the best food for our cats, it is very expensive!
We encourage home testing, not only as a way to determine Kit Kat's BG levels and make informed decisions about dosing, but also because it will allow you to do BG curves and share the results with your vet. Information on home testing is here
http://www.felinediabetes.com/FDMB/viewtopic.php?f=14&t=287. You do not have to purchase a glucometer made specifically for animals. In fact, many people here purchase their glucometer from Wal Mart.
In the event Kit Kat has a hypo incident, you need to be prepared with information on how to treat Kit Kat and the supplies you will need to have on hand. That information is here
http://www.felinediabetes.com/FDMB/viewtopic.php?f=14&t=2354 and here
http://www.felinediabetes.com/FDMB/viewtopic.php?f=14&t=1122.
Your vet will discuss what type of insulin to give Kit Kat. If you browse this forum, you'll see Insulin Support Groups (ISG's). In each of those forums, you will find information about the different insulins available.
You are going to have many questions...please post back, and we'll do our best to help and support you.