What kind if diabetes? Mellitus or insipidus? Mellitus is very very very rare in a young dog. Like unheard if rare. Insipidus could be congenital or trauma related.
Personally, I would be going to an Internest to figure out why your puppy has diabetes. In my 20 years as a vet tech, I have never seen a puppy with diabetes.
If it's congenital, I would look at my contract and see what it says.
Good luck with your puppy!!!!
"So that others may live"