Sentence:  If you give a small glucose load to 30 different people and do not allow for the fact that their basal blood sugars are all different, you may not see a significant rise in the mean blood sugar. Have you corrected your curves and tried to do these plots in terms of <WSD>incremence</WSD> and decremence from some starting point? 
Meaning of the word marked with <WSD> tags:  Incremental growth.