Infection Risk

Hyperglycemia does more than raise a glucose reading. It interferes with neutrophil movement, phagocytosis, and microbial killing, while also disrupting cytokine signaling. The immune response is present, but it may be slower and less effective. Diabetes can also reduce the body’s ability to reveal infection. Peripheral neuropathy may eliminate the pain that normally draws attention to a wound. Peripheral arterial disease limits tissue oxygenation and delivery of immune cells and antibiotics. A person can therefore have a deep foot infection with little pain, minimal fever, or only a modest white blood cell elevation. Infection then worsens glycemic control. Stress hormones such as cortisol and catecholamines increase insulin resistance and hepatic glucose release. This creates a dangerous cycle: infection raises glucose, and higher glucose further impairs host defenses. In insulin-deficient states, illness can precipitate diabetic ketoacidosis (DKA); severe dehydration and hyperglycemia can also progress to hyperosmolar hyperglycemic state (HHS). An unexplained sustained rise in glucose should prompt a search for infection, but it is not diagnostic by itself. Missed insulin, corticosteroids, enteral nutrition, pain, and physiologic stress can also raise glucose....