These articles indicate its effect with blood sugar +blood pressure.
http://www.livestrong.com/article/411513-olive-leaf-effects-on-diabetes/
http://www.about-olive-leaf-extract.com/olive-leaf-side-effects.html
Ive had some of the same issues with some herbs+supps= effecting blood sugar or blood pressure
These herbs+supps are especially hard to take early in the morning/when the weather is cold.... thats when my blood sugar/blood pressure is low at those times.