This is pretty interesting. She was getting ready to make her marathon debut but whenever she'd eat or drink anything on a long run she'd get light headed. 5 years ago, she'd gotten light headed when she had a gel shortly before a 3000 so she had been avoiding them.
At first, her partner thought it must just be in her head but now they realize she has rebound hypolycaemia.
Anyone know how you treat this? She has two brothers who are diabetic. It's tough to be marathoner when one is experienceing "low blood sugar levels during long training runs after taking energy drinks or gels."