Resistance or just new high needs

How do you know if you’ve suddenly (over a few months) developed any insulin resistance vs whether your body just drastically changed your insulin needs to a much greater amount?

Seems my relatively little insulin needs have skyrocketed in the last two months, to the point where nothing I ever did in the last 3+ years works anymore. Not my ratios, sensitivey rates, basals etc….nothing. How the **** can everything just change so fast when everything else has stayed consistent?