Just to pop something in from Ben Bikman, who has spent a lifetime studying insulin resistance:
The three direct causes of IR are:
1. Elevated Insulin (might seem pointlessly obvious, but the body will need more of anything over time to have the same effect)
2. Inflammation (of all types - and at all levels)
3. Elevated stress hormones
These three obviously can overlap, and one can cause another - stress can raise glucose which can raise insulin etc...
In that context - Covid 19 clearly increases inflammation - so it has a part to play in this, but all these effects can be shown in the lab to be quick and reversible - but over time can build up (have much longer-term effects on the cell structure) and therefore be less easy to reverse acute effects (from any infection, say).
The flip side of this, of course, is that anything you can do to reduce these three drivers will lower insulin resistance over time also.
How you do that is a totally different story....
