These black and white cats are something else... mine has us all the way up to 7.5u!
We have a similar story with our cat - lost a lot of weight (from ~22 down to 14). Our cat is still quite ravenous which I read is due to high BG values and the weight is very slowly coming back on (I think he's at 15 lbs now).
If Dyson is really thirsty still (maybe his coat isn't as nice or he's sleeping on the water bowl - like my cat!) someone recommended to me to add water to the pate meals to help with the fluid intake - this was very helpful!
At his two main meals, I add a whole 5.5oz can's worth of water to his food and mix it in well. He's so ravenous that it doesn't bother him to have it be watered down. Since doing this, my cat's coat is back to normal, not greasy flaky or unkempt, and he's not laying at the water bowl 24/7.
The fluid helps flush ketones.