Sick-Day

A fever, gastroenteritis, infection, injury, or surgery can raise blood glucose even when the person is eating very little. Illness triggers cortisol, catecholamines, glucagon, and growth hormone. These counter-regulatory hormones signal the liver to release glucose while making muscle and fat cells less responsive to insulin. Insulin deficiency changes this from hyperglycemia into a metabolic emergency. Without enough effective insulin, cells cannot use glucose well, so the body breaks down fat for fuel. The liver converts fatty acids into ketones. Ketones are acidic; rising ketones can therefore progress to diabetic ketoacidosis (DKA). Poor intake creates the opposite danger as well. A person taking insulin or a sulfonylurea may become hypoglycemic if carbohydrate intake falls. Sick-day care is a balancing task: prevent dehydration, detect ketosis early, avoid hypoglycemia, and maintain enough insulin to suppress ketone production.