As Sue says, in the early days, diabetic cats can eat-eat-eat and still feel hungry because they do not have enough insulin to get the energy from the food. -- the sugar (food energy) is just being lost in the urine.
The fact that you have been seeing some trace of KETONES is very worrying -- this can become serious quickly -- kitty needs more food and more insulin (ketones occur when the body is breaking down tissues to survive).
your BG numbers look reasonable -- I see you are from Australia -- are you actually measuring in these units or converting for us Americans? OH -- sorry -- I see it now in your spreadsheet
Most diabetics have lost weight prior to diagnosis, and gain weight after treatment has started (recovering what was lost)
In some cases, another condition is present which causes excessive weight gain. It is too early to tell if Little Boy has this yet, but I'll mention it anyway.
My first diabetic cat, Norton, had a condition called Acromegaly -- it caused his diabetes -- his pancreas was functioning. The condition produces excess growth hormone which interferes with the natural insulin. The excess growth hormone floating around inside the kitty causes various random parts to grow -- some "acrocats" have organ growth, some have larger body parts --
Norton had larger than average feet and was very muscular like a wrestler. He didn't look abnormal -- just stocky and very strong.
Anyway, going back to weight gain -- Norton had lost 2 pounds in the 2 months prior to FD diagnosis. After we started treating him with insulin, he gained back the 2 pounds PLUS 2 MORE!!! And it wasn't fat gained.