This patient with long-standing type 1 diabetes mellitus presents with signs and symptoms of diabetic ketoacidosis (DKA), namely acute onset polyuria, polydipsia, fatigue, weakness, hyperglycemia, and urine ketones. DKA, most commonly seen in type 1 diabetes mellitus, is caused by a stressful event that results in elevated blood glucose levels in the setting of insulin deficiency. Unopposed actions of stress hormones and glucagon result in hyperglycemia and lipolysis with intracellular metabolism of free fatty acids resulting in ketones. Peripheral insulin resistance resulting in elevated blood glucose and hyperosmolarity describes hyperosmolar hyperglycemic state (HHS), a complication commonly seen in type 2 diabetes mellitus. This infection likely did result in elevated blood glucose levels due to increase levels of circulating stress hormones and in fact may have precipitated the patient’s DKA. However, it does not describe the patient’s current condition of DKA. Dehydration can cause DKA sometimes through elevations in stress hormones and volume contraction, but this patient did not present with any signs of dehydration. It would also not account for the urine ketones.