After a steroid injection in my hand last year, my levels were in the low 20s later that day and in the teens for about a week. They said this was only a small dose. I had an accident on the way home, didn't know how much of the increase was from steroid and how much from pain and stress of having a suspected broken neck :roll: (somewhat stressful!) so corrected cautiously, having no idea how long it would last. Reckon I may have needed as much as 30% extra to keep BGs on target at first, tailing off over about 10 days.
Just my experience though, everyone's different.