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

Management of Hyperglycemia in the ICU

For ICU patients with hyperglycemia, initiate insulin therapy when blood glucose exceeds 180 mg/dL on two occasions within 24 hours, targeting a glucose range of 140-180 mg/dL using continuous intravenous insulin infusion. 1, 2

Treatment Threshold and Target Range

• Start insulin therapy at blood glucose ≥180 mg/dL (10.0 mmol/L) confirmed on two separate measurements within 24 hours 1, 2
• Target glucose of 140-180 mg/dL (7.8-10.0 mmol/L) is recommended for most critically ill patients 1, 2
• More stringent targets of 110-140 mg/dL (6.1-7.8 mmol/L) may be considered only for highly selected patients (such as cardiac surgery patients or those with acute ischemic cardiac/neurological events), and only if achievable without significant hypoglycemia 1, 2
• Never target glucose levels below 110 mg/dL (6.1 mmol/L), as this increases hypoglycemia risk and mortality without clinical benefit 2

The evidence supporting these targets comes from the landmark NICE-SUGAR trial, which demonstrated that intensive glucose control (81-108 mg/dL) resulted in significantly higher mortality (27.5% vs. 25%) and 10- to 15-fold greater rates of hypoglycemia compared to moderate control (140-180 mg/dL) 1.

Insulin Administration Method

Continuous intravenous insulin infusion (CII) is the mandatory method for glycemic control in ICU patients 2:

• IV insulin's short half-life (<15 minutes) allows rapid dose adjustments in response to changing clinical status, nutrition, or hemodynamic instability 2
• CII typically achieves target glucose levels within 4-8 hours 2
• Avoid subcutaneous insulin entirely in critically ill ICU patients, particularly during hypotension or shock, as absorption is unreliable and has not been formally studied in this population 2

Glucose Monitoring Protocol

• Perform point-of-care (POC) blood glucose monitoring every 30 minutes to 2 hours during IV insulin therapy 1
• Use FDA-approved, hospital-calibrated POC glucose monitoring systems 1
• For patients eating, check glucose before meals; for those not eating, monitor every 4-6 hours 1
• Computer-based algorithms for insulin infusion management reduce hypoglycemia rates and glycemic variability 2

Hypoglycemia Prevention and Management

Hypoglycemia is the primary safety concern and must be aggressively prevented 1, 2:

• Level 1 hypoglycemia: 54-69 mg/dL (3.0-3.8 mmol/L) - requires prompt treatment to prevent progression 1
• Level 2 hypoglycemia: <54 mg/dL (<3.0 mmol/L) - requires immediate intervention 1
• Level 3 hypoglycemia: altered mental/physical status requiring assistance - medical emergency 1
• Severe hypoglycemia (<40 mg/dL or 2.2 mmol/L) is associated with cognitive impairment and increased mortality 2

Critical Pitfalls to Avoid

• Never use sliding-scale insulin as the sole regimen - this results in undesirable glycemic fluctuations and increased hospital complications 2
• Do not pursue overly aggressive glucose targets (<110 mg/dL) - this increases hypoglycemia risk without improving outcomes and may increase mortality 1, 2
• Never use subcutaneous insulin in the acute ICU phase - absorption is unreliable during hemodynamic instability 2
• Inadequate glucose monitoring frequency during insulin infusion is dangerous 2

Special Considerations for Severe Hyperglycemia (>400 mg/dL)

When glucose exceeds 400 mg/dL, immediate assessment is required 3:

• Check arterial blood gases, complete blood count, urinalysis, plasma glucose, electrolytes, BUN, creatinine, and obtain ECG 3
• Start IV regular insulin bolus at 0.15 units/kg body weight, followed by continuous infusion at 0.1 units/kg/hour (typically 5-7 units/hour) 3
• Target glucose decline of 50-75 mg/dL per hour 3
• Begin fluid resuscitation with 0.9% normal saline at 10-20 ml/kg/hour (approximately 1-1.5 liters in first hour) 3
• Do not start insulin if potassium is <3.3 mEq/L - replete potassium first, as hypokalemia occurs in approximately 50% of patients during treatment and increases mortality 3
• Add 20-40 mEq/L potassium to IV fluids once renal function is confirmed 3

Transition from IV to Subcutaneous Insulin

When transitioning out of the ICU or off IV insulin 2, 3:

• Start subcutaneous basal insulin 1-2 hours before stopping IV infusion 3
• Calculate basal insulin dose as 60-80% of total daily IV insulin dose 3
• 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 3
• Ensure stable glucose measurements for at least 4-6 hours, resolution of acidosis (if present), hemodynamic stability, and stable nutrition plan before transitioning 2