Greetings, Bingo (is this kitty's name?) and pet parent. It's all a whirl at the beginning after the diabetes diagnosis. And, sometimes you just don't know which way to jump. But, you have come to the right place to learn about feline diabetes and effective treatment.
I have a long haired kitty too, and I agree, it's not always easy to find skin under all that luxuriant fur! I hope the previous responses help.
There are three main components of effective diabetic treatment, just like with humans: proper diet, insulin therapy and blood sugar testing. A human does not inject insulin without testing, and tests at different times to see how the insulin is affecting him/her.
I do hope you will consider home testing, it's the best way to keep your cat safe because you test before injecting, so you know the blood sugar is high enough to "shoot". Then you test when you can during the time between shots, so you can see how the insulin is affecting the cat, and how low the blood sugar (BG for blood glucose) level goes. If you are testing you will be able to see if that BG is too low, is a possible hypoglycemic event, and you can take action to bring the BG up.
We have links available to help you learn to home test, information about a proper low carb diet (which you are already exploring) and information on the type of insulin you are using, the NPH.
Julie told you about the Walmart ReliOn Prime meter and strips. That system works very well for many of our members, plus the strips are readily accessible. We went through a lot of strips learning to test, and we were using the pet meter and very expensive strips! You will need 26 or 28 gauge lancets, because getting that little blood sample isn't always easy at first.
Transitioning from the dry food to a low carb wet food is going to lower those BG numbers. You want to be testing first, however, so that you can see the change. The low carb food can significantly lower the BG and transitioning gradually is the best way to go. You don't want to abruptly change to wet low carb food and have the BG drop suddenly sending kitty into a hypo.
Please review the information about Novolin (NPH) insulin
HERE : The Beginner's Guide to N/NPH, so you know what you are dealing with better. Novolin is a fast acting "in & out" type of insulin, and there are others that are smoother acting and longer lasting that you may want to consider down the road.
Let us know how you want to proceed and what you want to learn about next, ok? I don't want to overwhelm you with information, but we do want to help you along the way.
Best wishes going forward.