Sick-Day

A viral illness, urinary infection, vomiting, or even severe pain can raise blood glucose despite poor food intake. Illness activates cortisol, catecholamines, glucagon, and growth hormone. These counter-regulatory hormones tell the liver to release glucose and make body tissues less responsive to insulin. For a person with little or no endogenous insulin, the problem extends beyond hyperglycemia. Cells cannot use glucose effectively, so the body breaks down fat for energy. The liver converts fatty acids into ketones. Ketones are acidic; accumulation produces diabetic ketoacidosis (DKA). This is why “I barely ate today, so I skipped my insulin” is dangerous. Food intake may fall, but the body’s insulin requirement does not disappear. Basal insulin suppresses glucose release from the liver and limits ketone production between meals. It must continue during illness unless a prescriber gives a different order. Fluid loss intensifies the crisis. Fever, tachypnea, vomiting, diarrhea, osmotic diuresis, and poor intake can rapidly produce dehydration. Reduced circulating volume lowers renal perfusion, decreases glucose clearance, and worsens hyperglycemia. An experienced nurse notices the combination: rising glucose, dry mucosa, decreasing urine output,...