Let's say you ate a good meal of complex carbohydrates, protein, and fat without any additives, chemicals, or bug repellent. As it starts to come down it also tells the liver to make enough blood sugar so it doesn't go too far down. We need the amino acids to make the hormone insulin and to rebuild the enzymes and tissues. Fats don't rebuild you, carbohydrates don't rebuild you, proteins rebuild you. I think that you are familiar with the fact that diabetics have a terrible time healing and one of the reasons is because without insulin they have hardly any protein metabolism.
Tiny cuts take forever to heal.
This to me is the best part because it really tells you what is going on. You are not eating and the blood sugar starts to drop. Your hypothalamus, which is like a little thermostat, goes ZIP, causing the sympathetic nervous system to send a signal down to your adrenal glands. If the liver puts too much glucose in, then insulin comes out and drives it back down again. The whole cycle is constantly going on to some degree.