Type 1 diabetic injected insufficient insulin so her body can’t use glucose in blood. Blood glucose is 38 mM (normal value = 3.3-5.8 mM). To adjust osmolality, she increased urine output = dehydration. Should she be treated with water?

Question

The answer is NO and my teacher said the following:
NO b/c water will dilute everything in body, and your gonna give insulin which will cause glucose to come out then all of the sudden not enough solutes in blood and it will come out of the blood = edema ; she would be given saline .9 soution of nacl = isotonic same osmality of blood; reason for this is because once you give insulin and glucose is taken up by cell, you wanan make sure everything is in the right compartments

This makes no sense to me at all. What does she mean it will dilute everything? Since she has polyuria Im thinking there are more solutes in her blood in comparison to water. Actually that's all I'm understanding here. To compensate would the cells release water? I'm confused.

Answer 1

I drew myself a picture and I think I may understand a little more. This is my new thinking. If you were to just give plain water then the water would be taken up by the cells b/c the solute:water ratio in the cells would be less than that in the blood so water would move from the blood to the cells. I'm thinking this because water must have left the cells to go into the blood at one point because the solute concentration must have been greater in the blood but once you add in the water it would more to the tissues because the tissues now have more solute than water. If you were to give saline, the water would remain in the blood stream because saline is a solute so since you added more solute you need more water so it'll stay in the blood. I don;t know much about the whole isotonic thing yet but this is kinda what I understand. It's stil kinda rough.