He was struggling with the same old food day in and day out. When I was diagnosed we changed his breakfast to sausage and eggs, wow, what a difference!
Then he got a tumor and for his sake it was time to say goodbye. He was 15.
Might it be worth contacting your vet or PDSA to ask if they could take them off your hands?
And I'm so sorry about your dog - one of my previous dogs was very poorly with heart disease when we put him to sleep and the only thing that kept me sane was knowing I could potentially help another dog by donating his poor heart for research, so I hope that trying to help another diabetic pet will be of some consolation to you.
I got my supplies online so the vets won't help. They can't guarantee that it has been stored correctly. I initially asked them to pass my phone number to anyone on with diabetic pet owners but nothing happened.