The patient described in the question stem is suffering from diabetic ketoacidosis (DKA). Patients with DKA are deficient in insulin and, therefore, have deficient cellular uptake of glucose.
DKA is a medical emergency that can occur in both type I and type II diabetics, though more commonly in type 1. Insulin deficiency and glucagon excess in DKA promote hyperglycemia and ketogenesis. As a result, anion gap metabolic acidosis, volume depletion, and dehydration occur. Left untreated, DKA can progress to coma and death. Insulin and glucagon oppose each other. Insulin promotes glucose, amino acid, and potassium uptake by cells. Glucagon promotes the formation of glucose (via glycogenolysis and gluconeogenesis), lipolysis, and formation of ketone bodies.
Trachtenbarg reviews the pathophysiology and treatment of DKA: "A diagnosis of diabetic ketoacidosis requires the patient's plasma glucose concentration to be above 250 mg per dL (although it usually is much higher), the pH level to be less than 7.30, and the bicarbonate level to be 18 mEq per L or less. Beta-hydroxybutyrate is a better measurement of the degree of ketosis than serum ketones. Intravenous insulin and fluid replacement are the mainstays of therapy, with careful monitoring of potassium levels."
Lee et. al., in a 2012 study in mice, found that although insulin deficiency is responsible for the symptoms of type I diabetes, "the metabolic manifestations of diabetes cannot occur without glucagon action and, once present, disappear promptly when glucagon action is abolished. Glucagon suppression should be a major therapeutic goal in diabetes.
Illustration A depicts the insulin-mediated cellular uptake of glucose via the GLUT-4 transporter.
Answer 1: The fruity odor on the patient's breath is caused by acetone, which is formed by ketogenesis.
Answer 2: Patients with DKA have markedly elevated serum glucose levels; readings as high as 800 mg/dL are not uncommon.
Answer 3: Patients with Addison's disease are deficient in cortisol. Patients in DKA would be more likely to have high cortisol levels as the body responds to the stress of the illness.
Answer 5: Patients with DKA have a deficiency of insulin and excess of glucagon.
Trachtenbarg DE. Diabetic ketoacidosis. Am Fam Physician. 2005 May 1;71(9):1705-14. Review.
PMID:15887449 (Link to Abstract)
Lee Y, Berglund ED, Wang MY, Fu X, Yu X, Charron MJ, Burgess SC, Unger RH. Metabolic manifestations of insulin deficiency do not occur without glucagon action. Proc Natl Acad Sci U S A. 2012 Sep 11;109(37):14972-6. doi: 10.1073/pnas.1205983109. Epub 2012 Aug 13.
PMID:22891336 (Link to Abstract)