I had this for years without knowing what it was. At its worst, I had to eat every 45 minutes or my brain would do that revving/screaming/wheels spinning thing (silently, I mean; I’m pretty sure no one else could hear it). If I drank fruit juice alone without food, I’d get woozy and almost pass out. Long periods without eating would leave me shaking and practically comatose. However, when my doctor tested me for it with blood tests and an oral glucose tolerance test, they came back negative.
All this resolved after I started taking magnesium and biotin. I don’t remember how much magnesium I had been on — 500 mg/day? — but when I added 2,000 mcg of biotin, after a few weeks I could go for eight hours without food without crashing, although I can’t guarantee I wasn’t surly and irritable.
This was actually an accidental discovery. I was taking the biotin and magnesium in an attempt to stop the hair loss, which it did, although the lost hair did not grow back in. The evened-out blood sugar was a pleasant byproduct of the experiment.