That is an excellent question. I wish I had an answer for you. Sounds so similar to what my brother is going through. He gets hypoglycemia and extra panic attack symptoms on top of it, so add to the symptoms you listed: heart palpitations, hyperventilation, severe dizziness, weakness, muscle twitching. So far, we've discovered that OJ helps to pull him out of it usually, sometimes within 10 minutes and other times it takes 45 minutes. Sometimes it doesn't work at all. His last attack was on and off for 3 days. He would keep drinking OJ, feel better, then relapse.
We do know from his visit to the naturopath that he definitely has adrenal fatigue. The doc just gently passed a light across the field of vision of my brothers eyes and it took his pupils a long time to respond. That's one test. The doc also checked his sitting-to-standing blood pressure and found that it dropped too many points when he stood up. That's the second test. If you suspect adrenal fatigue, a naturopath can confirm this. I do not know if a regular doctor has the knowledge to perform these simple tests, it's not really their specialty. Please let us know if you find any more information in the coming months, perhaps it will help my brother figure out what to do next as well.
BTW, even sugarless but sugary tasting foods can trigger insulin response, maybe that helps.