What is the initial approach to starting insulin in the Intensive Care Unit (ICU)?

Initial Approach to Starting Insulin in the ICU

For critically ill patients with persistent hyperglycemia (two consecutive blood glucose readings ≥180 mg/dL), continuous intravenous insulin infusion at a concentration of 1 unit/mL is the recommended initial approach. 1

Insulin Initiation Protocol

When to Start Insulin

• Initiate insulin therapy when blood glucose levels reach ≥180 mg/dL on two consecutive readings 1
• This trigger threshold is lower than the treatment goal to avoid prolonged periods above the target range

Method of Administration

• Continuous IV insulin infusion is strongly preferred over subcutaneous insulin for critically ill patients 1, 2
• Prepare insulin as a standardized concentration of 1 unit/mL 1
• Prime new tubing with a 20-mL waste volume before starting the infusion to prevent adsorption-related dosing errors 1

Initial Dosing

• Initial insulin bolus: 0.15 units/kg (for most critically ill patients) 2
• Initial infusion rate: 0.1 units/kg/hour 2
• For patients with diabetic ketoacidosis (DKA), use the same initial bolus and infusion rate with a blood glucose target of 250 mg/dL 2

Target Glucose Range and Monitoring

Target Range

• Maintain blood glucose between 140-180 mg/dL for most critically ill patients 1, 2
• More stringent goals (110-140 mg/dL) may be appropriate for select patients such as:
  • Cardiac surgery patients
  • Patients with acute ischemic cardiac events
  • Patients with acute neurological events 1

Monitoring Frequency

• During periods of glycemic instability: Monitor blood glucose every hour or more frequently 1
• Once stable: Can extend monitoring intervals, but maintain frequent monitoring during the first 24-48 hours 1
• Use validated point-of-care glucose meters or laboratory measurements 1

Protocol Implementation

Use of Decision Support Tools

• Implement a standardized insulin infusion protocol or algorithm 1
• Computer-based algorithms have been associated with:
  • Lower rates of hypoglycemia
  • Reduced glycemic variability
  • Higher percentage of glucose readings within target range 1

Factors Affecting Insulin Requirements

Several factors influence insulin requirements and should be considered when titrating the infusion 3:

• Body mass index
• History of diabetes
• Reason for ICU admission
• Admission hyperglycemia severity
• Caloric intake
• Time in ICU

Avoiding Complications

Preventing Hypoglycemia

• Implement a hypoglycemia management protocol 2
• For blood glucose <70 mg/dL: Administer 15-20g of fast-acting carbohydrate
• For blood glucose <60 mg/dL: Administer IV glucose immediately
• Highest risk of hypoglycemia occurs during the first 24 hours of insulin therapy 3

Transitioning from IV to Subcutaneous Insulin

When the patient is stable and ready to transition from IV to subcutaneous insulin:

1. Calculate total daily subcutaneous insulin dose using 50-60% of the 24-hour IV insulin requirement 2
2. Administer subcutaneous basal insulin 2 hours before discontinuing the IV insulin infusion 2
3. Split the total daily dose: 50% as basal insulin and 50% as prandial insulin 2

Special Considerations

Subcutaneous Insulin in the ICU

• Subcutaneous insulin should be avoided in critically ill patients, particularly during hypotension or shock 1
• May be considered in select stable ICU patients, but IV insulin is preferred for:
  • Type 1 diabetes
  • Hemodynamically unstable patients
  • Patients with changing clinical status (hypothermia, edema, frequent interruption of nutrition) 1

Insulin Requirements Over Time

• Insulin requirements are highest and most variable during the first 6 hours of intensive care 3
• Between days 7-12, insulin requirements typically decrease by approximately 40% on stable caloric intake 3

By following this structured approach to insulin initiation in the ICU, you can effectively manage hyperglycemia while minimizing the risks of both hypoglycemia and persistent hyperglycemia, ultimately improving patient outcomes.