Does blood sugar elevate during an acute illness?

Blood Sugar Elevation During Acute Illness

Yes, blood sugar commonly elevates during acute illness due to stress-induced hyperglycemia, which is an adaptive immune-neurohormonal response that increases metabolic substrates for struggling organs during crisis. 1, 2

Pathophysiology of Stress-Induced Hyperglycemia

• Acute illness triggers metabolic and endocrine abnormalities that lead to hyperglycemia, often called "stress diabetes" or "diabetes of injury" 1
• During acute stress, hepatic glucose production increases through upregulation of both gluconeogenesis and glycogenolysis 1, 3
• This occurs despite high serum insulin levels, indicating insulin resistance during acute illness 1
• Several hormonal factors contribute to this hyperglycemic state:
  • Increased levels of glucagon, cortisol, growth hormone, catecholamines, and cytokines 1, 3
  • These hormones stimulate glucose production and impair peripheral insulin-mediated glucose uptake 1

Prevalence and Clinical Significance

• Elevated serum glucose is common in the acute phase of illness, present in approximately two-thirds of patients with acute ischemic stroke 1
• Hyperglycemia during acute illness is associated with:
  • Increased mortality and morbidity 1, 2
  • Longer hospital stays (7 versus 6 days) 1
  • Higher healthcare costs ($6611 versus $5262) 1
  • Poorer clinical outcomes, particularly in patients without pre-existing diabetes 3, 4

Specific Effects in Different Acute Conditions

• In acute ischemic stroke:

  • Hyperglycemia is associated with infarct expansion and hemorrhagic conversion 1
  • The risk of hemorrhagic transformation increases by 75% per 100 mg/dL increase in blood glucose 1
  • Elevated glucose levels may prevent early reperfusion and reduce the benefit of thrombolytic therapy 1, 5

• In critical illness:

  • Hyperglycemia is linked to increased risk of in-hospital mortality and congestive heart failure 1
  • Even mild elevations of fasting glucose in patients with coronary artery disease undergoing procedures have been associated with substantial mortality risk 1

Metabolic Adaptation During Infection

• During infection, the body shifts to catabolic processes to meet increased energy demands 1
• Inflammatory cytokines (IL-1β, TNF) and stress hormones (cortisol) trigger these changes 1
• In early stages of infection, hyperglycemia redirects glucose to immune cells promoting aerobic glycolysis 1
• In later stages of sepsis, hypoglycemia may develop due to peripheral glucose usage and anorexia 1

Management Considerations

• The optimal glycemic target during acute illness remains undefined and may differ between patients and clinical settings 1
• Intensive insulin therapy to maintain normoglycemia has shown mixed results:
  • Some studies demonstrate reduced mortality and morbidity 1
  • Others show no significant benefit in clinical outcomes 1
• Current guidelines recommend:
  • Monitoring blood glucose levels during acute illness 1
  • Using rapid-acting insulin for blood glucose levels >140 mg/dL in acute ischemic stroke 1
  • Minimizing glycemic variability and avoiding hypoglycemia 1

Important Clinical Caveats

• Stress-induced hyperglycemia is not equivalent to a diagnosis of diabetes mellitus 2
• Blood glucose levels should be interpreted in the context of the patient's presenting complaint and previous glycemic status 2
• Patients who experience stress-induced hyperglycemia should be followed after recovery as they remain at risk for developing diabetes 2, 4
• Excessive immune activation resulting from enhanced glycolysis during hyperglycemia may sometimes do more harm than good 1