I think for some of us (I'm only looking at my peer group of T2, managing on diet) it's easier, from the perspective of managing the condition on a day to day basis to consider we have a carb intolerance. \i've certainly found that messaging easier to convey to non-Ds when they may ask why I'm not having pasta, burger bun or whatever, than try to explain anything else.
Of course elevated bloods and all that can, mainly over time, go along with them are reactions, not cause.
In my opinion Diabetes is a portfolio condition, in that there are many factor influencing how our bodies react to the way we live our lives. For some of us, insulin resistance is, or was, at the core of our condition, and for others taking certain longer term medications caused their bodies not to be able to maintain a non-diabetic state. As we read, genetics influence it, as well as potential pathological changes in other organs.
Over time, many of us piece together what may have tipped us over the edge, but for some it'll always seem to have been a lottery. That's no slight on anyone at all. For some it's straight forward and for some there are too many potentials in play.
Really all we can do is take the warnings of our various diagnosis and do our best to get whatever markers were cause for concern at diagnosis into a better place, and try to keep them there. Sometimes life just plays cruelly.