dont worry about your english it's fine
as for the peeing, maybe take him back in to the vet to have his sugar tested. if their pee his "like glue" do you think it's the pee or the cat litter? if there's too much sugar in the diet it'll come out in the urine, then the urine is literally sugary and sticky. as for the food, maybe ask your vet if they have any more affordable recommendations? or see if you can find other people with diabetic cats and ask what they feed?
"If you can't change your fate, change your attitude." - Amy Tan