My mom has vascular dementia and diabetes and it is managed with Glucophage XR and diet/exercise.
Google A1c diabetes technolgies.... you don't have to count on the NH to do tests.
We don't test for A1c but I do all the rest of the routine monitoring for diabetes, as well as her other vitals, myself. BP kit, stethascope, glucometer and cholesterol checker all ran a bit under 300.00 total. Got everything on ****.
Does FIL have a confirmed AD diagnosis? What stage? IME, diabetes can have a marked effect on transitory cognition. When mom eats properly, takes her meds on time, and is active, she is much more likely to have a "good" day.
A good friend of ours who's an RN told us diabetes will likely get her before any other health problems or her dementia. I took that advice to heart.
Pat