I dive with two diabetics, and one hydrophobic person. I have no issues diving with them.
One one hand, they have more dive experience than I do. On the other, if they are honest about their issues and what behaviors I should expect from them and what to specifically do if there is a problem, I am willing to be their buddy.
As an example, when I asked the hydrophobic diver, what should I expect if they should
"start freaking out", they said that they don't panic and maul their buddy, they just indicate that they want/need to surface NOW please. Our dives together have been uneventful, are
non deco dives and at least so far, as not been an issue. Just having a sympathetic buddy who they know accepts their issues, so far has relieved the stress enough that nothing untoward has occured on our dives. I wouldn't want to go deeper than 60', maybe, with them, so I have my own criteria...
With the diabetic divers, I interview them concerning what sort of medications they take,
how to recognize symptoms/problems and what actions to take. I also limit dives to about 60' with them, shore dives only.
I'm starting to insist that a new buddy do an OOA drill with me in shallow water before we
do our lst dives together. It gives me some measure of how that person will react under stress and task loading. I try to get them to do this on subsequent dives as well. It seems to be the best I can do to see if they'll be likely to be there for me if need be.
I also solo dive familiar sites (so guess I'm a dangerous diver) from time to time and carry a pony bottle or dive doubles for redundancy. so I try to be self reliant too.
Perhaps it's because I was a Special Education teacher for years that I feel more accepting of divers with health issues or feel that I can recognize whether something may become a dangerous situation before it does. Well...only time will tell for certain.