Can blood sugar levels be low during an infection?

Blood Sugar Levels During Infection

Yes, blood sugar can be low during an infection, particularly in later stages of sepsis, and hypoglycemia during infection is associated with increased mortality and requires urgent treatment.

Relationship Between Infection and Blood Glucose

Infections can affect blood glucose levels in multiple ways, with different patterns emerging depending on the stage and severity of infection:

Initial Hyperglycemia

• In the early stages of infection, particularly sepsis, hyperglycemia (high blood glucose) is commonly observed 1
• This occurs due to:
  • Dysregulation in glycogen metabolism
  • Significant insulin resistance
  • Inflammatory mediators that redirect glucose to immune cells 1

Later Hypoglycemia

• In later stages of sepsis or severe infection, hypoglycemia (low blood glucose) can develop 1
• Causes of infection-associated hypoglycemia include:
  • Peripheral glucose usage by tissues and immune cells
  • Infection-associated anorexia (reduced food intake)
  • Inflammatory cytokines like IL-1β that can directly induce hypoglycemia 1

Clinical Significance of Hypoglycemia During Infection

Hypoglycemia during infection is not just a laboratory finding but has significant clinical implications:

• Hypoglycemia was observed in 16.3% of Ugandan patients with sepsis on hospital admission 1
• Low blood glucose levels correlate with poor outcomes and organ dysfunction in sepsis patients 1
• Hypoglycemia during infection is independently associated with increased in-hospital mortality 1, 2
• A study of diabetic patients with infections found that hypoglycemia increased death risk by 266% 2

Monitoring and Management

Given the risk of hypoglycemia during infection:

1. Check blood glucose levels in every septic patient whenever possible 1, 3

2. Be especially vigilant in patients with:

   • Altered mental status (86% specificity for predicting hypoglycemia in septic patients) 1
   • Malaria and other specific infections 1
   • Limited glycogen stores (malnourished patients or those with liver disease) 1

3. Treatment of hypoglycemia during infection:

   • Administer 30-50g of glucose urgently for patients with low blood sugar 1, 3
   • Provide ongoing glucose calorie source to prevent recurrence 1
   • Aim to maintain blood glucose ≥70 mg/dL (≥4 mmol/L) 1, 3
   • Avoid targeting upper blood glucose levels <150 mg/dL (<8.3 mmol/L) due to risk of hypoglycemia 1, 3

Special Considerations

• If blood glucose testing is not immediately available in a patient with altered mental status and suspected infection, make a presumptive diagnosis of hypoglycemia and treat accordingly 1, 3
• Glycemic variability (fluctuations in glucose levels) during infection is also associated with increased mortality 2
• Patients with diabetes are at particular risk for both infection and complications from dysglycemia during infection 4, 5

Understanding the biphasic nature of glucose response to infection (initial hyperglycemia followed by potential hypoglycemia) is crucial for proper monitoring and management of patients with infections, especially those with sepsis.