Glycemic

A patient does not need a history of diabetes to develop clinically significant hyperglycemia in the hospital. Acute illness activates cortisol, catecholamines, glucagon, growth hormone, and inflammatory cytokines. These signals tell the liver to release glucose and make muscle and adipose tissue less responsive to insulin. The result is stress hyperglycemia: increased glucose production combined with insulin resistance. Several common treatments intensify this response. Glucocorticoids increase insulin resistance, enteral or parenteral nutrition provides a continuous carbohydrate load, vasopressors raise catecholamine effects, and surgery creates a metabolic stress response. A patient whose outpatient diabetes was well controlled may therefore need insulin temporarily during pneumonia, sepsis, trauma, myocardial infarction, or after an operation. Hyperglycemia is not merely a laboratory abnormality. Elevated glucose impairs leukocyte function, promotes infection, worsens osmotic diuresis and dehydration, delays healing, and is associated with longer hospitalization and higher mortality. The goal is not normal outpatient glucose values at all costs; aggressive lowering creates hypoglycemia, which is immediately dangerous in an acutely ill patient. For most hospitalized adults, treatment is initiated for persistent glucose at or above 180 mg/dL....