Lots of different possibilities for what is happening, but I will start with a very general rule which maybe does not always apply, but usually does.
- If you are trying to fix a high, use a bolus.
- If you are trying to prevent a high, use a basal, or temp basal, or the correct IC.
As time goes by, you get your basal tuned in better to what you will need.
But in general, trying to fix a BG of 200 by increasing your basal will be much slower than just bolusing to fix it, and then figuring out what your correct basal and IC should be to prevent if from happening next time.
Not sure if that makes sense. Lemme know if I should clarify.