Shouldn't come as a surprise - there are so many factors involved in glucose response to food that it's almost impossible to replicate a glucose response even with a controlled intake. Sleep, activity levels (before, after, during, even days before, etc), stress, hormones, all of these are major factors involved in how glucose is metabolized.
burnt-resistor|9 months ago
I think it will/would take a lot of data to uncover the most important factor(s).