What is the recommended insulin infusion protocol for critically ill patients in the Intensive Care Unit (ICU)?

Insulin Infusion Protocol in the ICU

Blood Glucose Targets

For most critically ill adults in the ICU, initiate insulin infusion when blood glucose exceeds 180 mg/dL and target a range of 140-180 mg/dL (7.8-10 mmol/L), avoiding lower intensive targets of 80-110 mg/dL due to increased hypoglycemia risk without mortality benefit. 1

• The 2024 Society of Critical Care Medicine guidelines explicitly recommend against titrating insulin infusions to lower intensive targets (4.4-7.7 mmol/L or 80-110 mg/dL) based on high-certainty evidence showing increased severe hypoglycemia (RR 4.0) without improvement in mortality 1
• More stringent targets of 110-140 mg/dL may be appropriate for select cardiac surgery patients, but only if achievable without significant hypoglycemia 2, 3
• The American Diabetes Association recommends the 140-180 mg/dL target range for most ICU patients 2, 3

When to Initiate Insulin Infusion

Start continuous intravenous insulin infusion when blood glucose persistently exceeds 180 mg/dL on two occasions. 1, 3

• Persistent hyperglycemia ≥180 mg/dL is associated with endothelial dysfunction, inflammation, and potentially increased mortality, particularly in non-diabetic patients 1
• Consider adjusting fluids, nutrition, or medications causing hyperglycemia before or concurrent with insulin initiation 1

Protocol Characteristics

ICUs must implement a standardized, validated insulin infusion protocol that includes computerized decision support when possible, as this approach reduces hypoglycemia and improves time in target range compared to paper-based or ad hoc protocols. 1

Essential Protocol Components:

• Validated insulin administration algorithm with predefined adjustments based on glycemic fluctuations 1, 2
• Computerized decision-support systems achieve better glucose control and lower hypoglycemia rates than paper-based protocols (demonstrated in multiple RCTs) 1
• Adequate staffing resources trained in protocol use 1
• Accurate monitoring technologies with awareness of point-of-care glucose meter limitations 1
• Robust data platform to monitor protocol performance and clinical outcomes 1

Insulin Dosing Approach:

• Start with 0.1 units/kg/hour (typically 5-7 units/hour in adults) after an optional 0.15 units/kg IV bolus 3
• Use regular insulin for continuous IV infusion 3
• Adjust infusion rate based on current blood glucose and rate of glucose change 4

Monitoring Requirements

Monitor blood glucose every 30 minutes to 2 hours during active insulin infusion titration, with frequency adjusted based on glucose stability. 3

• More frequent monitoring (every 30-60 minutes) is required during initial titration or when making dose adjustments 3
• Once stable in target range, monitoring can be extended to every 1-2 hours 3
• Be aware that point-of-care glucose meters may lack accuracy in critically ill patients with anemia, hypoxia, or certain interfering medications 1

Hypoglycemia Prevention and Management

Implement strict hypoglycemia prevention protocols, as even brief severe hypoglycemia (BG ≤40 mg/dL) is independently associated with increased mortality. 1

Critical Hypoglycemia Thresholds:

• BG ≤70 mg/dL is associated with increased mortality 1
• BG ≤40 mg/dL (severe hypoglycemia) carries significant mortality risk that increases with prolonged or frequent episodes 1
• Intensive insulin protocols increase severe hypoglycemia risk 5-fold (OR 5.18) 1

Safety Measures:

• Treat hypoglycemia immediately without delay 1
• Mandate independent double-check of insulin doses 1
• Use prominent product labeling and avoid abbreviations like "U" for units 1
• Implement standardized hypoglycemia treatment protocols 2, 3
• Monitor particularly during overnight hours when hypoglycemia risk is highest 3

Population-Specific Considerations

Cardiac Surgery Patients:

• Target BG <150 mg/dL in the postoperative period to reduce deep sternal wound infection and mortality 1
• This population showed mortality benefit with moderate glucose control in subgroup analysis 1

Trauma Patients:

• Initiate insulin when BG ≥150 mg/dL, targeting <150 mg/dL but maintaining absolutely <180 mg/dL to achieve lower infection rates and shorter ICU stays 1
• Use protocols with demonstrated low hypoglycemia rates (BG ≤70 mg/dL) 1

Neurologic Injury Patients:

• Exercise extreme caution as tight glucose control may induce regional neuroglycopenia in traumatic brain injury 1
• Severe hypoglycemia can produce or exacerbate focal neurological deficits, seizures, and permanent cognitive dysfunction 1
• Insufficient evidence exists for specific targets; manage like general ICU patients with heightened vigilance for hypoglycemia 1

Transition to Subcutaneous Insulin

Administer subcutaneous basal insulin 2-4 hours BEFORE discontinuing the IV infusion to prevent rebound hyperglycemia. 2, 3

• Calculate total daily subcutaneous dose as 60-80% of the insulin infusion rate during the prior 6-8 hours when stable glycemic goals were achieved 2
• Transition only when patient is stable with glucose consistently <200 mg/dL and able to eat 3
• Distribute as 50% basal insulin and 50% rapid-acting prandial insulin divided before three meals 3

Critical Safety Pitfalls to Avoid

• Never use sliding scale insulin alone as the sole regimen—this increases both hypoglycemia and hyperglycemia risk and worsens hospital complications 2, 3
• Avoid factitious glucose elevations from icodextrin peritoneal dialysis solutions or maltodextrin-containing medications when using glucose dehydrogenase monitoring systems 1
• Do not draw blood glucose samples through arterial lines with dextrose-containing flush solutions, as this can cause fatal errors 1
• Ensure protocols do not have excessive insulin bolus rates, which have been associated with harm in some studies 1
• Limit severe hypoglycemia rates to <5% of patients as a quality benchmark 1

Quality Metrics and Performance Monitoring

Continuously monitor protocol performance using standardized metrics to ensure safety and efficacy. 1, 3

• Track percentage of glucose values within target range (140-180 mg/dL) 3
• Monitor hypoglycemia rates (both <70 mg/dL and <40 mg/dL) 3
• Analyze time to reach target glucose range 5
• Document all insulin administration and subsequent glucose readings 3
• Perform detailed multiprofessional analysis of actual errors and near-miss events 1
• Reassess protocol immediately if adequate glucose control is not achieved or frequent hypoglycemia occurs 1