I think it's more complex than a what came first (but as with anything there are going to be people who are the exception).
Diabetic A: Does all the things they are supposed to do, enjoys good glycemic control, sees their doctor twice a year, has good labs and overall is in good health. They stub their toe and after 3 months of 3x a week visits to the wound care clinic it doesn't heal and they have the toe amputated. Inpatient they seem to do pretty well in terms of coping and seem to take it all in stride.
Diabetic B: Does all the things they are supposed to, their blood sugars are all over the place, they are in the doctors office monthly, their BP is rising and their renal function is declining and they never feel 'good'. They stub their toe and after 3 months of 3x a week visits to the wound care clinic it doesn't heal and they are admitted to have the toe amputated. Inpatient they are a basket case with no apparent ability to cope with what has and is happening.
Who has better coping skills?
With chronic illness/disability it's the 'hits' (big and small) that can add up until you hit the wall.
Sometimes what pushes you over is something minor.
How much anyone can take is as individual as pain tolerance, with many if not all the same variables.
With chronic illness/disability so many tasks that are so simple that most people don't give them any thought, aren't simple. Often, normal every day tasks require more time, thought and effort.
Think about what going grocery shopping involves for you (the collective you).
When I go grocery shopping I do all the same thing, ie; make a list, find my wallet, grab my keys, hop in the car and go. Except I also have to make sure I have my grabber and my backpack of supplies and once I get out the door I have to transfer into the car, dismantle and load my chair.
My choice of store is limited based on my experiences as to which ones have a bathroom I can actually use, how helpful the employees are and even if the handicap cutouts in the sidewalk are too steep (many of them are).
Once I get to the store I have to circle the parking lot until I can get a parking spot with the correct orientation, unload and assemble my chair and transfer into it. My purchases are limited to what I can carry in my lap or hang off my chair, my choices are limited to what I can reach with or without a grabber or asking a passerby to reach something for me.
Last week while loading up to go home after a trip to the grocery store I smacked myself in the glasses with a footrest. I sat in my car and cried for 10 minutes. I just wanted to surprise my husband with his favorite dinner and that minor blow to the face was, at that point, just too much. It was the straw that broke the camels back for me.
As I said above, with chronic illness/disability it's the 'hits' (big and small) that can add up until you hit the wall. Sometimes what pushes you over is something minor.
But it's more than just that.
Sometimes those minor hits that add up and that push you over, come in rapid succession and you never really get the chance to recover in between. Consequently it takes fewer hits to push you over and eventually you lose the ability to recover at all (at least for a little while).