I have been LC for several years and had a set of labs drawn, mostly all were great but FBG was 110. I was freakin'.
I bought an UltraMini OneTouch ($20) and 100 test strips ($100) and had a blast!
I tested my FBG every morning for a week, it was always between 90-110. Then I started checking it every hour til I ate my first meal at 11am, I found it dropped about 5 points every hour and was always around 80 just before lunch.
Then I would eat and test every 15 minutes. If I eat a big potato with nothing else, my blood sugar goes like this in 15 min increments: 80, 115, 115, 140, 170, 140, 120, 100, 80, 60, 80 , 80 then stabilizes til supper. If I eat an all-protein/fat lunch, it does this: 80, 100, 100, 120, 120, 100, 100, 80, 80 then stabilizes til supper.
They all say it should be less that 140 two hours after eating. That's more important than anything!
Here's a link to an article with a graph of the normal variances seen in healthy people.
Bottom line, normal is a wide range, your individual response to glucose is the key. The only way to accurately say you are diabetic or have impaired insulin sensitivity is with an hbA1C test. Otherwise, buy a home tester and chart your response to different foods just for the heck of it.
Fasting - 70-99 mg/dL (3.9-5.5 mmol/L) considered “normal”
Post-meal - <140 mg/dL (7.8 mmol/L) considered “normal”