Disclaimer: I do not know what I'm talking about. Assuming both numbers are accurate (I haven't double checked any of the numbers above), the discrepancy could

Disclaimer: I do not know what I'm talking about. Assuming both numbers are accurate (I haven't double checked any of the numbers above), the discrepancy could be with time. Your body doesn't just have sugar in its blood. It uses it. At any given moment "Average blood sugar" needs to be 5grams. However throughout the day your body burns up 97.5 grams (I.e. 39 grams is 40%).