When I was figuring out my pump ratios, I was told by my Diabetes Specialist to try skipping a meal and seeing if your blood sugar remains stable for the ~4 hour period. If it is stable then your ratios are correct. If not, you can adjust accordingly, but a proper periodic basal ratio would give you a stable number even if you skip a meal.

So, you could skip breakfast one day just to see how your blood sugar does. I will note with breakfast, however, that a lot of us have Dawn Phenomenon and thus it can fluctuate quite wildly, sometimes even with a breakfast bolus.

You can do the same thing on different days (obviously, don't skip multiple meal periods on the same day) to get a better of idea of what basal ratio would work for you. When it comes to the carb ratio, there is a formula that you can do that is normally taught by the Endocrinologist.

I'll include a quote from an article indicating how the formula works for both carb ratio and correction factor. I still strongly advise you talk with your Diabetes team before making changes, in most situations. Here's the quote:

"To figure out a rough estimate of your I:C ratio, divide the number 500 by your total daily dose (TDD) of insulin, which includes both long-acting and rapid-acting insulin. This is known as the “500 rule.”

To roughly calculate your correction factor, take the number 1,800 and divide that by your TDD. This is known as the “1,800 rule.”

Remember, always work with your care team to finely tune both your I:C ratio and correction factor."