Your diabetic patient asks you why he "passes out" when his blood sugar gets too low. Which of the following responses is most accurate?

A) "When the blood sugar is low, the brain does not get enough oxygen."
B) "Brain cells need a constant supply of glucose, or sugar, to function. Without sugar the brain cells cannot work to maintain consciousness."
C) "When the blood sugar is low, the blood vessels relax and the blood pressure drops, causing you to faint."
D) "The cells of the heart can only use glucose, or sugar, for energy. Without sugar the heart cannot effectively pump blood to the brain."

B