What insulin protocol is used in critically ill patients with hyperglycemia?

Insulin Protocol for Critically Ill Patients

Continuous intravenous insulin infusion is the preferred protocol for managing hyperglycemia in critically ill patients, prepared at a standardized concentration of 1 unit/mL using human regular insulin, with initiation when blood glucose reaches ≥150-180 mg/dL. 1, 2

Route of Administration

Intravenous insulin infusion is strongly preferred over subcutaneous insulin in the acute management of critically ill patients with hyperglycemia. 1

When IV Insulin is Mandatory:

• Type 1 diabetes mellitus 1
• Hemodynamically unstable patients (on vasopressors) 1
• Changing clinical status (hypothermia, peripheral edema, frequent interruption of nutrition) 1
• Significant hyperglycemia (two consecutive blood glucose >200 mg/dL) 1

When Subcutaneous Insulin May Be Considered:

• Stable ICU patients only, after resolution of acute illness 1
• Must meet all criteria: no planned interruptions of nutrition, peripheral edema resolved, off vasopressors 1
• If subcutaneous regimen fails to maintain blood glucose <180 mg/dL, immediately resume IV insulin infusion 1

Protocol Preparation and Administration

• Prepare insulin at 1 unit/mL concentration using human regular insulin 1, 2
• Prime new IV tubing with 20-mL waste volume before connecting to patient 1, 2
• Use continuous infusion rather than intermittent boluses for rapid titration capability 1

Blood Glucose Targets

Initiate insulin infusion when blood glucose ≥150 mg/dL, with an absolute upper limit of <180 mg/dL maintained at all times. 1, 2

Target Range:

• Avoid tight glycemic control (80-110 mg/dL) due to increased mortality risk 1
• Target range of 140-180 mg/dL is recommended for most critically ill adults 1
• The 2024 SCCM guidelines suggest against targeting 80-139 mg/dL compared to 140-200 mg/dL to reduce hypoglycemia risk 1

Glucose Monitoring Frequency

Monitor blood glucose every 1-2 hours during active insulin infusion; never use 4-hourly intervals as this is associated with hypoglycemia rates >10%. 2

Monitoring Considerations:

• Frequent monitoring (≤1 hour intervals) is suggested during periods of glycemic instability 1
• Point-of-care glucose meters may have significant variability in critically ill patients, particularly with anemia, hypoxia, or vasopressor use 2
• Confirm unexpectedly high or low values with laboratory measurement when clinical picture doesn't match 2

Clinical Decision Support Tools

Use a protocol that includes explicit clinical decision support tools (computerized or structured algorithms) rather than protocols without such tools. 1

Evidence for Decision Support:

• Computerized protocols achieve better glucose control than paper-based "if-then" systems 1
• Reminder alerts lead to more consistent and timely blood glucose assessments 1
• Lower hypoglycemia rates consistently demonstrated with computerized protocols 1

Hypoglycemia Prevention and Management

The updated Yale insulin infusion protocol demonstrates excellent safety with only 0.3% of glucose values <70 mg/dL and 0.02% <40 mg/dL. 2, 3

Hypoglycemia Response:

• For blood glucose <70 mg/dL: immediately reassess and modify insulin regimen 2
• For symptomatic or severe hypoglycemia: administer IV dextrose (preferred over glucagon for faster response) 2
• Protocols must include immediate, protocolized treatment by nurses without delay 1

Nutritional Considerations

Evaluate the amount and timing of carbohydrate intake when calculating insulin requirements, and include specific instructions for unplanned discontinuation of nutrition. 1, 2

Key Points:

• Consistent nutrition intake simplifies glycemic management during insulin infusion 1
• Protocols must address unplanned discontinuation of enteral feeding, parenteral nutrition, or dextrose infusions to prevent hypoglycemia 1, 2
• Avoid overfeeding, which produces hyperglycemia requiring higher insulin doses 1

Transition Off IV Insulin

Transition stable ICU patients to a protocol-driven basal/bolus subcutaneous insulin regimen BEFORE stopping the insulin infusion to avoid loss of glycemic control. 1, 2

Transition Protocol:

• Use basal-bolus regimen with scheduled basal insulin plus prandial and correction doses 2, 4
• Delay transition until: no planned interruptions of nutrition, peripheral edema resolved, off vasopressors 1
• Protocol-driven transition leads to better glucose control than non-protocol therapy 1

Safety Considerations

Insulin is a high-alert medication accounting for approximately one-third of all major drug-related injurious medication errors in hospitals. 1, 2

Safety Strategies:

• Standardized protocols for insulin dosing and monitoring 1
• Independent double-check of doses 1
• Minimize available insulin products to reduce confusion 1
• Avoid abbreviations such as "U" for units 1
• Prominent product labeling and storage away from other medications 1

Common Pitfalls to Avoid

• Never use sliding-scale insulin alone in critically ill patients—it results in poor glycemic control and increased complications 4, 5
• Do not use 4-hourly glucose monitoring during active insulin infusion 2
• Do not rely solely on point-of-care meters without understanding their limitations in critically ill patients 2
• Never stop IV insulin before initiating subcutaneous insulin in transitioning patients 1