Stress hyperglycemia is a temporary, acute elevation of blood glucose that occurs during physical stress, trauma, or severe illness, even in individuals without a prior diagnosis of diabetes. This phenomenon is commonly observed in hospital settings, particularly in intensive care units, and serves as a marker of the body’s systemic response to acute injury or infection. The condition is defined as a blood glucose level above 180 mg/dL in a patient without pre-existing diabetes. Unlike chronic diabetes, this elevated sugar level is transient and typically resolves once the underlying medical crisis is managed, but it signals a severe physiological disturbance and is associated with poorer outcomes in critically ill patients.
The Hormonal Mechanism Behind Glucose Spikes
The sudden rise in glucose is initiated by the body’s protective “fight or flight” response, which aims to provide an immediate surge of energy. When the body encounters severe physical stress, such as major surgery, traumatic injury, or serious infection, the nervous and endocrine systems rapidly activate. This stress response triggers the release of counter-regulatory hormones, primarily cortisol and catecholamines like adrenaline and noradrenaline.
These hormones disrupt normal glucose regulation in two distinct ways. First, they instruct the liver to increase the production and release of glucose into the bloodstream through glycogenolysis and gluconeogenesis, flooding the circulation with emergency fuel. Second, these stress hormones simultaneously induce insulin resistance in the body’s tissues, meaning cells become less responsive to insulin.
Insulin, which moves glucose from the blood into the cells, becomes ineffective due to this resistance. The combination of the liver overproducing glucose and the body’s cells refusing to take it up results in a rapid spike in blood sugar levels. Inflammatory cytokines, also released during severe illness, further worsen this metabolic environment.
Common Acute Illnesses That Trigger the Condition
Stress hyperglycemia is a common finding across severe medical conditions. Acute infections, particularly sepsis, are powerful triggers for this condition, as the systemic inflammatory response drives significant hormonal and metabolic changes.
Major cardiovascular events, such as acute myocardial infarction, frequently lead to stress hyperglycemia. Neurological emergencies, including ischemic stroke and subarachnoid hemorrhage, also correlate strongly with elevated blood sugar upon admission. Furthermore, significant physical trauma, such as severe burns or major surgical procedures, reliably activates the hormonal pathways causing this temporary glucose spike.
Why Temporary High Sugar Levels Are Dangerous
Acute stress hyperglycemia carries significant risks beyond those associated with chronic diabetes. Elevated glucose levels impair immune system function, making it difficult for the body to fight off the underlying infection or injury. This impairment increases the risk of hospital-acquired infections and leads to poorer outcomes, especially in patients with sepsis.
High glucose promotes increased inflammation and oxidative stress within the body’s tissues. This inflammatory state can hinder the healing process, increasing the risk of wound complications after surgery. In conditions like heart attack or stroke, stress hyperglycemia is associated with larger areas of tissue damage and a higher incidence of complications like cardiogenic shock or increased mortality.
The presence of stress hyperglycemia is often a powerful predictor of adverse outcomes, including longer hospital stays and higher mortality rates. The acute, uncontrolled glucose surge can directly damage blood vessels and organs. This temporary metabolic derangement often resolves once the patient’s acute illness is successfully treated and the systemic stress subsides.
Treatment and Monitoring During Acute Episodes
Managing stress hyperglycemia focuses on rapidly and safely bringing blood glucose levels down to a target range. The standard approach, particularly for critically ill patients, involves continuous intravenous insulin infusion, allowing medical staff to achieve precise and rapid control over glucose levels.
Intensive glucose monitoring is performed frequently, often hourly, to ensure glucose remains in the therapeutic range and prevent hypoglycemia. Clinical guidelines recommend maintaining levels between 140 and 180 mg/dL for most critically ill patients. Once the patient stabilizes, the continuous intravenous insulin is transitioned to a subcutaneous regimen. As the acute illness resolves, the need for intensive insulin therapy diminishes. Treatment is typically temporary, though follow-up screening for future diabetes may be required.