If a type 1 diabetic has not taken any insulin in a day and a half, but has been eating as they would regulary would their blood sugar levels be high or low? And would it be dangerously so? Also, because of the blood sugar level would they light-headed or tired or something like that? Detailed answered are appreciated, thanks in advance.

Your blood sugars can become dangerously high, and cause a condition called diabetic ketoacidosis (DKA). When you do not take your insulin, your body cannot use the sugars in food for energy, so it burns fat instead. When your body uses fats, ketones--an acidic byproduct--are produced. These build up in your bloodstream, and can make you very tired and dizzy. DKA is a serios complication of diabetes, and requires stablization in the ICU.