Steroids unfortunately will impact your BG levels, causing them to rise. It's a normal and useful physiological result of this type of chemical.
For example, your body naturally produces a hormone called Cortisol, which itself is a steroid. This is a "stress hormone" and causes a BG increase. More stress, more need for energy (fight or flight) and thus makes glucose more available to you.
Normally the body would use this BG via insulin, but as we're special it just floats around in our blood :-(
Transient, short term increases aren't a major concern. Your levels, even on the preds are still quite good. If you're not on these preds too long I wouldn't worry too much.
I would say tweak your insulin but this itself can be dangerous as you could misjudge.
Call your DN?