My dear uncle has diabetes requiring insulin after every meal. He takes care of himself but makes a scene testing his blood sugar and injecting his insulin at the table. This is done whether he is home, visiting others or at a restaurant. I respect my uncle but I am uncomfortable seeing needles and injections at the dinner table. I believe others are offended as well. I don’t want to hurt his feelings so I am need of guidance.
I understand that this situation certainly can be uncomfortable. Many people are not comfortable around needles. Have you spoken to your uncle? Possibly because of his condition, he has had to get comfortable with all that is associated with his diabetes. That could cause him to forget that others are not so comfortable with the process to keep his diabetes in check. A gentle conversation with him may help the situation.