Advice needed about a steriod injection

Steroid medications as you rightly mentioned do interfere with blood/glucose metabalism, causing them to rise, however with a one of injection I myself wouldn't be too concerned over this. and wouldn't even bother to amend my own medications.
However, had the Steroid medication been administered over a much longer time period, or maybe needed to run for a full regular daily course, then it might well be advisable to mention this to you Dr. who in such cases will commonly increase the dosage of the steriod medications and specifiy that the increased dosage is to be taken at 2 day intervals, so that on the day's when the steroid medication isn't taken, the body will then work better at stabilising the enevitable blood/glucose rises that they produce more effectively.
This usually applies to a Type 2, Type 1 and those on Insulin may well need to increase their Insulin dosage to compensate for the Steroid medication, but this should be decided upon by the patients Dr.
I hope this answers your question.

Short answer is yes.

I had a single corticosteroid injection in my hand and it raised my glucose levels for several days by just enough to concern me as I wasn't told this could happen so had to do some research to discover what was going on. However the rise I saw was much less than I might expect if I was eating high carb/sugary foods, and my levels came back down by themselves and I had no other issues, and it fixed the problem with my hand.

There have been a couple of other recent threads on the forum about peoples' experiences with steroid injections, so if you're interested, have a little search for them.

Robbity