Hi Lauren, welcome to the group. The members here will need a bit more information about your cat in order to help. Could you please set up your signature with some general information. This so we don't have to adk the same questions over and over. To do this you go to your name at the top right of the page. Click and you will get a drop down box. On the left you see signature. Click on this and tell us some basic information. Cats name, age and weight, date of diagnosis, what insulin you are using, the dose you are currently on. Blood glucose meter you're using and where you are located or timezone. If the cat has any other medical issues please note these too.
Are you home testing? It is important so that you know how low the insulin is taking his BG. and whether its safe to shoot insulin. There is a spreadsheet that we use here and it links to your signature so members can see what a dose is doing to the BG's before they can offer advice. You will find instructions on Tech support.
This is a wonderful forum and members are always willing to help. There is a wealth of experience and knowledge. I know you are probably overwhelmed with the diagnosis but you have taken a giant step to help your furbaby get to better health. Again welcome.