[BriOnH]

I always plot my glucose levels against time and vs carbs, insulin, and exercise; I think we all do this in our heads quite frequently.

Thinking out loud here; a frequency histogram (in this case) is going to be your fasting blood glucose level population (hopefully taken at the same time everyday. how big is this population? the > the population is the more accurate you can trend) against the frequency of which you hit that particular BGL. What are your centers under those two (Gaussian) curves? Are they that far apart in respects to the variance in BGL? Assuming they are...

You have a big variance in your frequencies to achieve a trend of a double Gauss. That variance, in the end, will always rely apon one of a few critical factors. What you eat, how much insulin you take, your activity level, what your other hormones are doing. So in your split of frequencies in what you would like to see versus what you actually get will rely on those factors. Only you could guess/know (unless I saw your data, but no thanks hehe) what factors those are to normalize your data.