๐Ÿ”ถ Stress Hyperglycemia in Critical Illness


๐Ÿ” 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.


๐Ÿงช Why Does It Happen? โ€“ Pathophysiology

Mechanism

Effect

๐Ÿ”ธ โ†‘ Catecholamines (epinephrine, norepinephrine)

Stimulate glycogenolysis, gluconeogenesis

๐Ÿ”ธ โ†‘ Cortisol, GH, glucagon

Antagonize insulin, โ†‘ hepatic glucose output

๐Ÿ”ธ โ†‘ Pro-inflammatory cytokines (TNF-ฮฑ, IL-6)

Induce insulin resistance

๐Ÿ”ธ โ†“ Insulin secretion/action

Impaired glucose uptake in muscle/adipose

๐Ÿ”ธ Exogenous glucose, vasopressors, steroids

Iatrogenic contributors


๐Ÿ‘‰ These all lead to hyperglycemia despite no prior diabetes.


๐Ÿฉบ Clinical Relevance in ICU:

System

Impact of Stress Hyperglycemia

๐Ÿง  CNS

Aggravates ischemic brain injury, delirium

๐Ÿซ Pulmonary

โ†‘ risk of infections (e.g., VAP)

โค๏ธ Cardiovascular

Associated with worse outcomes in MI

๐Ÿงซ Immune System

Impairs leukocyte function, โ†‘ infection risk

๐Ÿงฝ Wound Healing

Delayed granulation, โ†‘ surgical site infections

๐Ÿฉธ Coagulation

Promotes endothelial dysfunction, thrombosis

๐Ÿงฌ Metabolic

Aggravates catabolism, โ†‘ oxidative stress



๐Ÿ“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 (โ‰ฅ6.5%)

Glucose trend after illness

Normalizes

Persistent hyperglycemia

C-peptide

Normal or โ†‘

May be low or variable



๐Ÿ“ˆ Blood Glucose Targets in ICU

Patient Type

Target Range (mg/dL)

Notes

Critically ill (general ICU)

140โ€“180 mg/dL

Avoid both hyperglycemia and hypoglycemia

Cardiac surgery patients

110โ€“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



๐Ÿ’‰ 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


๐Ÿงช 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


๐Ÿง  ICU Mnemonic: “STRESS” Hyperglycemia

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


๐Ÿ“š High-Yield Research:

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


๐Ÿ”‘ 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.