How is hyperglycemia managed in the Intensive Care Unit (ICU)?

Management of Hyperglycemia in the ICU

Initiation Threshold and Target Range

Start insulin therapy when blood glucose exceeds 180 mg/dL (10 mmol/L) and maintain glucose between 140-180 mg/dL (7.8-10.0 mmol/L) for most ICU patients. 1

• The 180 mg/dL threshold is recommended by the American Diabetes Association, Society of Critical Care Medicine, and Society of Thoracic Surgeons as the trigger point for initiating insulin in critically ill patients 1, 2
• This target range balances glycemic control against hypoglycemia risk, which is associated with increased mortality 1
• More stringent targets of 110-140 mg/dL may be considered only for highly select patients (cardiac surgery, acute ischemic cardiac/neurological events), and only when achievable without significant hypoglycemia 1
• Avoid glucose targets below 110 mg/dL (6.1 mmol/L)—the Endocrine Society explicitly warns against this due to increased hypoglycemia risk without additional clinical benefit 1

Insulin Delivery Method

Use continuous intravenous insulin infusion (CII) as the preferred method for glycemic control in the ICU. 1

• The American Association of Clinical Endocrinologists specifically recommends CII over subcutaneous insulin for critically ill patients 1
• IV insulin's short half-life (<15 minutes) allows rapid dose adjustments in response to the unpredictable changes in nutrition and clinical status common in ICU patients 1
• CII typically achieves target glucose levels within 4-8 hours 1
• Avoid subcutaneous insulin in critically ill ICU patients, particularly during hypotension or shock, as absorption is unreliable and dangerous during hemodynamic instability 1

Initial Insulin Dosing Protocol

For severe hyperglycemia (>400 mg/dL), give an initial IV bolus of regular insulin at 0.15 units/kg body weight, followed by continuous infusion at 0.1 units/kg/hour (typically 5-7 units/hour in adults). 2

• Target a glucose decline of 50-75 mg/dL per hour 2
• If glucose does not fall by 50 mg/dL in the first hour, verify adequate hydration, then double the insulin infusion rate hourly until achieving steady decline 2
• For less severe hyperglycemia (180-400 mg/dL), start with continuous infusion without bolus, using computerized or validated written protocols 1, 2

Critical Monitoring Requirements

Monitor blood glucose frequently to prevent hypoglycemia, which is defined as <70 mg/dL (3.9 mmol/L) and represents a significant adverse event. 1

• Severe hypoglycemia (<40 mg/dL or 2.2 mmol/L) is associated with cognitive impairment and increased mortality 1
• Computer-based algorithms for insulin infusion management have shown benefits including lower rates of hypoglycemia and reduced glycemic variability 1
• Monitor potassium levels closely—hypokalemia occurs in approximately 50% of patients during treatment of hyperglycemic crises 2
• Do not start insulin if potassium is <3.3 mEq/L until potassium is repleted 2
• Add 20-40 mEq/L potassium to IV fluids (2/3 KCl and 1/3 KPO4) once renal function is confirmed 2

Fluid Management for Severe Hyperglycemia

Start with 0.9% normal saline at 10-20 ml/kg/hour (approximately 1-1.5 liters in the first hour for adults) for fluid resuscitation. 2

• In severely dehydrated patients, repeat this bolus but do not exceed 50 ml/kg over the first 4 hours 2
• Continue fluid therapy at 1.5 times the 24-hour maintenance requirements (approximately 5 ml/kg/hour) to replace deficit evenly over 48 hours 2
• Switch to 0.45-0.9% NaCl based on corrected serum sodium levels, ensuring osmolality decrease does not exceed 3 mOsm/kg/H2O per hour 2

Common Pitfalls to Avoid

Never use sliding scale insulin as the sole regimen—it results in undesirable glycemic fluctuations and is associated with poor outcomes. 1, 2

• Setting overly stringent glucose targets (<110 mg/dL) increases hypoglycemia risk without improving outcomes 1, 3
• Inadequate monitoring of glucose levels during insulin infusion is a common and dangerous pitfall 1
• Do not stop IV insulin abruptly—ensure 1-2 hour overlap with subcutaneous insulin when transitioning to prevent rebound hyperglycemia 2
• Avoid subcutaneous insulin of any type in the acute ICU phase for critically ill patients 1

Transition to Subcutaneous Insulin

Start subcutaneous basal insulin 1-2 hours before stopping IV infusion when discontinuing IV insulin after glucose stabilization. 2

• Calculate basal insulin dose as 60-80% of total daily IV insulin dose 2
• Use half of the 24-hour IV insulin total as long-acting basal insulin, and divide the other half by 3 for rapid-acting insulin doses before meals 2
• Ensure hemodynamic stability, stable glucose measurements for at least 4-6 hours, resolution of acidosis (if present), and stable nutrition plan before transitioning 1