What is the primary risk of a patient not receiving insulin over a few days?

The primary risk of a patient not receiving insulin over a few days is indeed the buildup of ketones leading to acidosis. In the absence of insulin, the body is unable to effectively utilize glucose for energy, which leads to a state of hyperglycemia. To compensate for this lack of glucose, the body begins to break down fat for fuel. This process results in the production of ketones, which are acidic byproducts. An excessive accumulation of ketones in the bloodstream can lead to diabetic ketoacidosis (DKA), a serious and potentially life-threatening condition characterized by a significant drop in blood pH.

In contrast, a rapid drop in blood glucose levels is more likely to occur when insulin is administered rather than withheld. Decrease in blood pressure is not a direct consequence of not receiving insulin for a few days; it typically relates more to fluid status and other factors rather than directly to insulin therapy. A right-to-left shunt is a cardiopulmonary condition generally unrelated to insulin or diabetes management. Thus, the concern surrounding insulin deficiency mainly revolves around metabolic derangements like ketoacidosis rather than these other factors.