Any time we get 2 high readings in a row (more than 250), after doing a correction, then we test for ketones...and change the site (we're on the pump...that is my son is...it's funny how it becomes a 'family' affair, isn't it?).
We've been very lucky that he's never had more than trace ketones...except for three days ago, when out of nowhere, he was in the mid 200s, so we tested, and very high ketones....changed sites, and with endo's advice, all ended up ok.
Mom to 2 boys (8 & 10), oldest dx in Oct. '06
Pump MM522 w/ Sure-Ts infusion sets since July '10
Previously pump Deltec Cozmo w/ Contact-Detach sets
"He attacked everything in life with a mix of extraordinary genius and naive incompetence, and it was often difficult to tell which was which." ~ Douglas Adams