It would be very helpful if you could take a few minutes to set up your signature and a spreadsheet. The information is in this
post on helping us to help you.
Issues like when it's safe to shoot (usually a number above 300 is fine) but a lot can depend on the context for the number. Is it a number that has dropped considerably from your last test or what insulin you're using or what approach to dosing you decided on. In most cases, experienced members who routinely open a spreadsheet before giving any advice will not offer input without a spreadsheet. (We're very number dependent.) Seeing the numbers insures that we're keeping your cat safe to say nothing of it allowing you to track your cat's progress.
There is a great deal of information about food on this website on
feline nutrition. There's a
chart on the website that lists out most of the canned foods available in the US along with information on their carbohydrates. Low carb is considered under 10% although most people use food that's in the neighborhood of 5%. It's also important to have some medium carb (10 - 15%) and high carb (over 15% like Fancy Feast Gravy Lovers) on hand in case you need to steer low numbers.
If you get a timed feeder, you can leave food out for when you're away from home.