Diabetic ketoacidosis
Now there is much more glucose in the bloodstream than in the cells.  The body always tries to stay in homeostasis.  In homeostasis, there would be an equal amount of sugar in the bloodstream and the cells.  To try to make this happen, the cells (which have very little sugar in them) give up water to the blood (which is very sugary).  The goal is to try to dilute the sugar in the blood, and decrease the high levels of hyperglycemia.  If the cells give up too much water, they can get dehydrated (not have enough fluid left in them).  Because DKA also causes a person to urinate often, a person with DKA can get dehydrated very quickly.  This dehydration can be a medical emergency.