Welcome to FDMB, although I'm sorry your kitty was diagnosed with diabetes. Often, an infection can raise blood glucose values, so I'm wondering how big of a role the UTI is playing in your kitty's numbers. (What's her name, by the way?) Was the diabetes "caught" at a routine vet visit, or was she showing signs of illness? Often, diabetic cats will drink and urinate excessively when their blood sugar levels are high.
What type of insulin were you given? Jersey was first prescribed Humulin, which is a very harsh insulin that brings kitty's blood sugar levels down quickly. It's actually not recommended here for the treatment of diabetes. Lantus, Levemir, and Prozinc are the most widely recommended insulins.
Here, most people do recommend feeding low-carb canned food. Have you seen Dr. Pierson's food chart yet? Here's a link to it just in case:
http://catinfo.org/docs/FoodChartPublic9-22-12.pdf Generally, cats do best on foods that are less than 10% carbs (third column in the cart). A lot of people here feed Fancy Feast classics or some of the low-carb Friskies varieties. (My vet convinced me to use Hill's w/d dry food in the beginning. I later found it that it was just as bad as the Meow Mix she had been eating. He was not happy when I refused to buy more of it when we went back for a checkup. :YMSIGH: )
Okay, let's talk about home testing for a second. Going to the vet can certainly raise blood sugar values (sometimes by 100 points or more), so testing at home gives us more accurate results. Would you be willing to learn to test at home? I know it sounds awful, scary, etc.....but it's truly not as bad as it sounds. And it's the best way to keep kitty safe.
I'm actually a bit torn on my advice to you. I feel like the UTI could be playing a huge role here, and I'm thinking it's resolution might bring down the blood sugar levels. I'm thinking a food switch might also bring down the numbers. The numbers at the vet's office could have been stress-induced, too. With all of these factors coming into play....and if you can't test at home, part of me is hesitant to recommend starting insulin tonight. (If we can help you get started testing at home, we'll be able to see what's going on a bit more clearly.) Please keep in mind that I am not one of the most experienced members here. I'm just throwing out some of my thoughts based on what I've learned with my own kitty. I hope other experienced users will be able to share their insights, too.
Shelly
EDIT: I cross-posted with BJ. Sorry for the repeat of some of the info in her post! ohmygod_smile