A week after getting my first pump my cannula came out overnight, and I woke up feeling very ill with blood sugar reading HI and quite high ketones, but managed to get normal blood sugars back without going into hospital thankfully. It was a steep learning curve, but I'm convinced it was the pump that saved me from going into hospital (whilst recognising it was the pump that caused the issue in the first place!!), and also that I hadn't got an underlying illness that was causing the high levels.
We're all different, and I think it depends what causes the very high blood sugars in the first place, whether you're confident in treating them yourself, if your blood sugar and ketone levels start reducing, etc, etc.
If my high levels hadn't started responding to treatment at home, then I'd have got medical help as appropriate of course.