My answer to If you have diabetes, how can you prevent fainting?
Answer by Connie b. Dellobuono:
Low glucose, lack of potassium and iron can cause fainting.
Potassium:sodium ratio is about 5:1 . Both can be found in whole foods, greens.
Iron rich foods include molasses and dark chocolates. Nuts and small seeds have calcium,magnesium and iron.
Dehydration (by excess loss of water in urine in diabetics), hormonal fluctuations and lack of sleep can cause fainting. In seniors, it is more of lack of potassium and in pregnant women, progesterone hormones widening the blood vessels.