Hi Sandi
Have you discussed your concerns with his doctor?
Alcoholism is a disease and unfortunately it can put a lot strain on a family.
It's very possible the alcohol is adding to his paranoia.
I understand when an elderly loved one puts demands on us. Many of on the site have been discussing the toll it takes on us mentally and physically.
Try talking to his doctor, ask him about the alcohol, has his doctor seen a change in him since the last time he went for a check up?
Is he being treated for his diabetes? If he's unwilling to go to the doctor you can use the diabetes as an excuse to get him to see the doctor, but first give the doctor a heads up on what is going on with your dad. I know there are laws (HIPPA) but this is you voicing your concerns to his doctor, by looking out for him.
If it is dementia then it will need to be addressed. They may need to a CT Scan or MRI to check the brain for any changes. Dementia runs in my family on both sides.
Aging stinks, I've been watching my grandmother decline and now I see changes in my mom, it's a tough process to deal with.
Your not alone we are all here for you.
Hang in there..