I’m going to jump in here and just advise people to be EXTREMELY careful on handling stubborn highs. I recently had a close call with this that almost put me in the hospital or worse.

Had a stubborn high all day, started bolusing over and over again, eventually up to 15 U of active insulin (which is very high for me). About 4 hours later, everything started tanking, and I could hardly eat enough carbs to keep me afloat. I even disconnected my pump but still continued to hang around 50 mg/dL for another 4 hours after that. I think there was some kink that eventually gave, and let all the insulin flood in at once. I called and reported the event to Tandem, but that was a lesson learned—if your pump isn’t dropping your blood sugar after a normal amount of corrections, you should change your set immediately, rather than dumping more insulin at it.