There has been a lot of discussion about what "normal" is. Here is a graph that gives a good indication of what it should be. The graph below is the average CGMS results of 21 young, healthy non-diabetics. It is from an interesting study. Before meals and at night, the mean BG value trickles along at about 80. And it doesn't go much higher than 120 after meals.
It is interesting that there is such a lot of variability above and below the mean. I guess it goes to show that non-diabetics can also be insulin resistant. I was also interested in the extent of the breakfast post-prandial excursion. To see the presentation and listen to the audio, go here :
www.diabetes-symposium.org