I live with my grandpa age 85 he has dementia and anger issues.. he also has taken to peeing any where out side.. in the grass.. on the side of the house and just off the front porch.... but we mention the fact about diapers he will get mad... what are some other things we can do.. he will pee in this pants and just keep wearing them and spray cologne on them to make it ok.
My Dad refused to wear any type of pee catching garment and my Mom had to clean up after him. Eventually Mom decided it was time for Dad to clean up his own messes.... lo and behold he asked for Depends and Depends Guards to wear.
As for peeing outside, may I ask if you live far apart from your neighbors? If so, let it be. Otherwise, if you live in a regular neighborhood, someone could call the police on your Grandpa for indecent exposure.
You are talking about medical problems. These are things that GP cannot help, because of damage to his brain. The first approach should be a medical one. Dementia is not curable but many of the symptoms can be treated for an improved quality of life.
If you've pursued all the medical help that is available, I wonder if it is time for GP to move into a care center where they are prepared to handle this behavior.