What Causes Disorientation In A Person With Heart Disease And Diabetes?

Hi, I would like some advise on how to proceed. My sister-in-law just told me that her husband is being very paranoid. He is 57 years old, diabetic, has high blood pressure, and has a heart condition (pace maker). He is currently not trusting her at all, saying that she is conspiring with others to get him. He said that people are getting in the house and that there are cameras. He sometimes hears his wife telling him something when she hasn t. He is supposed to go for cataract surgery in two weeks and has a 29 year old son whom he is taking care of more often lately (the son attempted suicide about a year and a half ago and now needs assistance). My husband, who is his youngdest brother, is planning to talk to him and I would like some advice on how he should approach the subject so that he doesn t feel we are conspiring against him. My brother-in-law is stubborn and we ll likely have a hard time to get him to go to the doctor. Any help would be greatly appreciated.