46 yo female elite marathoner, no personal or family history of diabetes, 100 lbs, 5'2" in excellent health ran 10K. Felt good and surged last mile of race and by finish slowed dramatically had difficulty breathing, became light-headed and weak, blood sugar tested 328 (repeated twice, third test 228). No further symptoms. What caused this?

Its my guess she didn't eat well enough the night before, or the morning of her race.

Stress on the body can easily raise blood sugar.

I don't understand you blood sugar testing methods. The numbers mean nothing to me. We have different terminology hereCanada whereby my blood sugar in the morning is anything under 7 which is recommended for diabetics to be before eating (8 after eating).

I wonder why one simple testing solution isn't universal which would probably be safer for everyone.

Maybe J-9 can explain the numbers above and why they differ from the way I test.

Runners have very high core temps if they don't have enough fluid during a race.And if not enough fluid can lead to death. I wonder if this would change the glucuse level ?

In the US, acceptable numbers are between 70 and 110.