I agree with the former posts...check thyroid, check insulin.
Another possible cause is low cholesterol. I am having a similar problem as you are with feeling rage for several hours after eating something that has sugar in it. The rage can be delayed for anywhere from 4 to 12 hours after eating the sugary food. I have only had this problem since I stopped eating dairy and eggs and soy (I used to be a vegetarian) and started eating small portions of lean meats (turkey, chicken, salmon, shrimp). I believe my cholesterol is too low and it's affecting brain function and causing a sensitivity to blood sugar. (you can google "irritability, rage, low cholesterol" and see all the studies done showing the link)
It also doesn't seem to make a difference what the sugar source is. If it's from sweet ripe fruit, or from several cookies, or from a cup of tea with a spoonful of table sugar, or even if I use agave syrup or honey...I end up with rage.
How are your insulin numbers? The first time I did my test, my glucose numbers after eating were around 122, but my insulin numbers where way too high. Showing I had insulin resistance. My body was producing too much insulin to keep blood sugar levels fine.
This might not be your case
have your thyroid tested use the free t3 and t4
as well as tsh