How long do you need high blood sugars in order to get ketones? Kind of an odd question… I’ve been having issues with my pump, that are getting resolved now, but no matter how long I was over 250 (on one day, that was all day, with shots!) I never get ketones. Is that just how my body works? Or should I open a new bottle of ketone strips next time? I don’t want ketones, though 
Actually, I think you also need to have your insulin go low to trigger ketones. Just going over 250 mg/dl does not necessarily do it. Nice try (just kidding). It is always a good practice to test for ketones when high like that. You only need to open a new bottle of strips when they expire. While the vial itself lists an expiry date, that is for an unopened vial. I think you will find many strips expire 90 days after opening. It is a good idea to write on the vial when you open them. I mean who can remember this stuff. They do make foil wrapped strips which last a lot longer. That being said, I have a bottle that is like two years old and they still register when I have ketones from low carbing. I would not necessarily trust them to keep me out of DKA.
Good question.
If you were drinking a good deal of water when high, ketones would be flushed out & not register.