My insulin levels are still at 17.1mu/L on keto. At what serum number mu/L would I no longer be considered insulin resistant?

18 months in & insulin levels down from 31.8 mu/L to 17.1 mu/L which is great but I'm disappointed that they're still quite high levels.

My GP says she wants me to be under 5mu/L which is a long term goal of mine, but she says there is no universal number for being 'no longer insulin resistant', but then I don't understand how they can decide I'm IR - surely there is a number they look at to be able to separate who has IR and who doesn't?