Yes, tension/stress can have an effect on your numbers. However, the changes are more likely caused in lifestyle changes, (eating, not eating, what goes in your mouth and when) related to the stress/tension. Slow down, examine your life, and get things back in line. Remember that a mother duck gets her ducklings in a line by having them follow her, rather than trying to herd them. The tools you mention are a great help in getting things under control. Whenever I let mine get out of control, the best thing is to record everything. Looking at the results is informative, but the acts of checking and recording helps center your attention on what is actually happening.
Remember, I said "do as I say, not as I do". Diabetes gets easy to ignore after a while, but it always catches up with me.