I don't think there is any finite explanation beyond what you have already learned unless you have a glucose tolerance test. I doubt it has anything directly related to your concussion. There is a saying, Correlation does not mean causation.

Sometimes, low blood sugar can trigger an adrenaline response as a signal for the body to release more blood sugar. This would cause the jitters.

If you have periods where you do not have access to food, try to keep some hard candies available. I've even had to eat a sugar cube back when I would have these experiences in college.