If cortisol is getting near 10 I consider that a problem. Adrenal fatigue has different phases and low cortisol is sort of an end game. Quite a complex thing overall and can’t do simple generalizations. That is why I direct folks to read Wilson’s book.
We have one guy here who had an unpleasant outcome with IR. He got quite vocal about anyone doing IR. I can’t see a heart risk that could be any different from someone restoring normal thyroid function with Rx thyroid meds. And I can’t see that been an issue unless one was very fragile already.
My criteria for adrenal fatigue is rT3 centric. If fT3 is adequate and body temperatures are low, I suspect that rT3 is the problem. Then one can test rT3 or assume that is the problem. There are places that guys here are from where that labwork is not available. There are other things that can reduce mitochondrial metabolic rates, such as low CoQ10, often induced by statin drugs.