No, I don’t know anyone. Since I no longer have a diabetic cat, my visits to the FDMB message board are too infrequent to have helped in this situation.
When I adopted my most recent 2 cats, I went to Ellen M. Gifford Cat Shelter in Brighton MA. They had a couple of diabetic cats being fostered. So at least they might know of someone that could help Claire in her search for a pet sitter. 617-787-8872 is the shelters phone number. Allston and Brighton are adjoining neighborhoods in Boston.
That’s the only thing I can think of for you to try Claire.