Hi and welcome to FDMB
When cats are diagnosed with FD many of them have lost weight and have a ravenous appetite. That is because the body can't absorb all the nutrients from the food because of the high blood sugars (BSLs). Once the BSL come more under control, the body starts to absorb more of the nutrients and the cat is less hungry. By the look of your SS he is coming down nicely into blue numbers. That is very probably what has happened but keep an eye on his appetite and getting his weight back to normal.
Are you feeding him just twice a day or several smaller meals over the course of the day. Many of us feed at preshot then at +3 or 4 and then again at +6, then do the same in the evening. It is better for the pancreas to have several smaller meals than just one big one. Depending on the insulin you are using, you might have to feed a largish meal preshot. But with the longer lasting insulins like Lantus and levemir it is OK to feed preshot and smaller meals during the day.
What insulin are you using?
You might like to fill in your signature with info such as his name and yours, type and dose of insulin, any other illnesses, type of glucose meter you are using, country you live in. Have you decided whether you will follow the tight regulation protocol or the start low, go slow protocol......if you have decided add that too. Go to the top right of the page and under your user name you will find signature. Press on that and fill in. It helps to have all your info in the signature as people who help you will look at it to find out information about your kitty.
Ask lots of questions. It is a steep learning curve in the beginning and a bit overwhelming but you will soon be an old hand at it all.
