πŸ”Ά Stress Hyperglycemia in Critical Illness


πŸ” Definition:

Stress hyperglycemia is transient elevation in blood glucose during acute illness or physiological stress, in patients without known diabetes.

  • Typically BG >140 mg/dL (7.8 mmol/L) in hospitalized or critically ill patients.
  • Can occur even in those with normal baseline glucose tolerance.


πŸ§ͺ Why Does It Happen? – Pathophysiology

Mechanism

Effect

πŸ”Έ ↑ Catecholamines (epinephrine, norepinephrine)

Stimulate glycogenolysis, gluconeogenesis

πŸ”Έ ↑ Cortisol, GH, glucagon

Antagonize insulin, ↑ hepatic glucose output

πŸ”Έ ↑ Pro-inflammatory cytokines (TNF-Ξ±, IL-6)

Induce insulin resistance

πŸ”Έ ↓ Insulin secretion/action

Impaired glucose uptake in muscle/adipose

πŸ”Έ Exogenous glucose, vasopressors, steroids

Iatrogenic contributors


πŸ‘‰ These all lead to hyperglycemia despite no prior diabetes.


🩺 Clinical Relevance in ICU:

System

Impact of Stress Hyperglycemia

🧠 CNS

Aggravates ischemic brain injury, delirium

🫁 Pulmonary

↑ risk of infections (e.g., VAP)

❀️ Cardiovascular

Associated with worse outcomes in MI

🧫 Immune System

Impairs leukocyte function, ↑ infection risk

🧽 Wound Healing

Delayed granulation, ↑ surgical site infections

🩸 Coagulation

Promotes endothelial dysfunction, thrombosis

🧬 Metabolic

Aggravates catabolism, ↑ oxidative stress



πŸ“Š How to Differentiate from Diabetes Mellitus

Feature

Stress Hyperglycemia

Undiagnosed Diabetes Mellitus

Fasting glucose (post-recovery)

Returns to normal

Remains elevated

HbA1c

Normal (<5.7%)

Elevated (β‰₯6.5%)

Glucose trend after illness

Normalizes

Persistent hyperglycemia

C-peptide

Normal or ↑

May be low or variable



πŸ“ˆ Blood Glucose Targets in ICU

Patient Type

Target Range (mg/dL)

Notes

Critically ill (general ICU)

140–180 mg/dL

Avoid both hyperglycemia and hypoglycemia

Cardiac surgery patients

110–140 mg/dL (tighter control)

Controversial; risk of hypoglycemia must be weighed

Non-critically ill (hospitalized)

Pre-meal <140, random <180** mg/dL

Use basal-bolus insulin regimens



πŸ’‰ Management Principles

  1. Frequent glucose monitoring (q4h or hourly if on insulin)
  2. Insulin infusion protocols (preferred in ICU)
  3. Avoid:
    • Sliding scale insulin monotherapy
    • Overcorrection (hypoglycemia risk)
  1. Reassess need for long-term glucose-lowering therapy after recovery


πŸ§ͺ Laboratory Considerations

  • HbA1c: Useful to differentiate chronic vs stress hyperglycemia
  • Monitor electrolytes, ketones, acid-base status (especially in sepsis or DKA-like states)
  • C-peptide or insulin levels: rarely needed but may help in unclear cases


🧠 ICU Mnemonic: “STRESS” Hyperglycemia

S – Sepsis
T – Trauma / TBI
R – Respiratory failure
E – Endocrine surge (cortisol, catecholamines)
S – Surgery
S – Steroids


πŸ“š High-Yield Research:

  • NICE-SUGAR Trial (2009): Tight glucose control (81–108 mg/dL) in ICU increased mortality compared to moderate control (140–180 mg/dL).
  • Emphasized moderate glycemic control is safer.


πŸ”‘ Summary Takeaways:

  • Stress hyperglycemia is a marker of severity, not just a lab abnormality.
  • Avoid both extremes: hyperglycemia (>180) and hypoglycemia (<70).
  • Post-ICU, patients with stress hyperglycemia should be evaluated for new-onset diabetes.