Depending what insulin you're taking it will act over a longer or shorter period, but even a rapid-acting insulin will probably have a peak effect around two hours, and still be working after five hours. After the different peaks, do you finish at the same level or different levels?
If after five to six hours, with no more food or insulin, your glucose levels are similar then it's a timing issue.
If the final levels are different, and activity is the same, you wake at the same time, injection sites are similar (insulin works more slowly injected into fat than muscle) then something else may be affecting your metabolism.
It doesn't appear to have been overnight since you're starting from the same blood glucose - unless you know different?
A sensitivity to the food you eat, for example wheat, or to an environmental factor could be driving it. It could also be a consequence of the night before; something in the morning may be tipping you over.