Stress hyperglycemia is a temporary increase in blood glucose levels that occurs when the body is under physiological duress, such as a severe illness, injury, or surgery. This condition can arise in individuals with no prior history of diabetes and resolves once the underlying cause of the stress is treated. This reaction is part of the body’s “fight-or-flight” response, which signals the adrenal glands to release a surge of stress hormones like cortisol and catecholamines. This response is graded, so a more severe stressor leads to a greater hormonal release and higher blood sugar.
The Physiological Response to Stress
The rush of stress hormones directly impacts the body’s regulation of blood glucose. Cortisol and catecholamines signal the liver to increase glucose production through two processes: glycogenolysis and gluconeogenesis. Glycogenolysis is the breakdown of stored glucose (glycogen) in the liver for a quick fuel source. Simultaneously, gluconeogenesis is the creation of new glucose from non-carbohydrate sources, like amino acids, ensuring a sustained energy supply.
This hormonal surge also affects how the body uses insulin. Cortisol, catecholamines, and inflammatory substances called cytokines make the body’s tissues temporarily resistant to insulin’s effects. This means peripheral tissues like muscle and fat cells cannot effectively take up glucose from the blood. This resistance ensures that newly released glucose remains in the bloodstream and is readily available for the brain and immune cells. The combined effect of increased glucose production and decreased glucose uptake leads to high blood sugar.
While beneficial for short-term survival, this response can become problematic if the stress is prolonged. The high levels of circulating glucose and inflammatory markers can have negative consequences, which is why the condition is closely monitored in hospitals.
Triggers and At-Risk Populations
Stress hyperglycemia is caused by profound physiological stress, not everyday psychological pressures. While emotional stress can affect blood sugar, it rarely causes the significant hyperglycemia seen in hospital settings. The most common triggers are acute medical conditions that require hospitalization.
These include:
- Sepsis, a body-wide inflammatory response to infection
- Major cardiovascular events like a heart attack or stroke
- Significant physical trauma from accidents or severe burns
- Complex or lengthy surgical procedures
The primary population at risk consists of critically ill patients, especially those admitted to an ICU, regardless of whether they have pre-existing diabetes. It is estimated that at least half of all critically ill patients experience some degree of stress hyperglycemia within the first 48 hours of admission.
Identifying Stress Hyperglycemia
In many clinical settings, stress hyperglycemia presents no outward symptoms. Patients may be sedated or unconscious, or their symptoms are masked by the underlying illness or injury. The condition is therefore identified through routine blood glucose monitoring, which is a standard procedure for these patients.
For conscious patients, the symptoms can mirror those of general hyperglycemia, including excessive thirst, frequent urination, and blurred vision. However, these symptoms are non-specific and can be overlooked or attributed to the primary medical condition.
A diagnosis is confirmed by blood tests showing glucose levels above 180 mg/dL in a patient without a prior diagnosis of diabetes. Healthcare providers must differentiate this state from undiagnosed diabetes. This may involve reviewing the patient’s medical history and measuring HbA1c levels, which estimate average blood sugar over the preceding months. A normal HbA1c level strongly suggests the condition is stress-induced.
Management and Treatment Approaches
The management of stress hyperglycemia occurs in a hospital and focuses on two goals: stabilizing blood glucose and treating the root cause of the stress. Addressing the underlying illness or injury is the most definitive step, as blood sugar levels will normalize once the stressor is controlled. For example, as a patient recovers from surgery or an infection, the hormonal cascade subsides and blood sugar returns to normal.
While the primary condition is being treated, healthcare providers actively manage the patient’s blood sugar with insulin. Critically ill patients in the ICU often receive an intravenous insulin infusion, which allows for precise, continuous adjustments to the dose. This method enables tight control over blood glucose levels in response to rapid changes in the patient’s condition.
In less critical situations or as a patient’s condition improves, subcutaneous (under-the-skin) insulin injections may be used. The goal is to maintain levels within a safe range, preventing the complications of severe hyperglycemia. Close blood glucose monitoring is performed to guide insulin therapy and avoid hypoglycemia, or dangerously low blood sugar.