Can insulin boluses be used with ongoing insulin infusions?

Insulin Boluses with Ongoing Insulin Infusions

Yes, insulin boluses can and should be used with ongoing insulin infusions to optimize glycemic control, particularly for meal coverage and correction of hyperglycemia. 1

Insulin Management in Hospital Settings

Critical Care Setting

• Continuous intravenous insulin infusion is the primary method for glycemic control in critically ill patients 1
• When using continuous IV insulin infusion:
  • Follow validated written or computerized protocols that allow for predefined adjustments based on glucose values 1
  • For diabetic ketoacidosis (DKA), either fixed-rate infusion or nurse-driven variable rate protocols can be used 1
  • Target blood glucose range: 140-180 mg/dL (7.8-10 mmol/L) for most ICU patients 1

Non-Critical Care Setting

• Basal-bolus insulin regimen is preferred for hospitalized patients with diabetes 1
  • Basal insulin: Provides background insulin coverage
  • Bolus insulin: Administered before meals or every 4-6 hours if patient is not eating
  • Correction insulin: Added to address hyperglycemia

Bolus Administration with Ongoing Insulin Delivery

Subcutaneous Insulin Pumps

• Continuous subcutaneous insulin infusion (CSII) delivers basal insulin continuously while allowing for bolus doses 1
• Bolus doses can be administered through the pump for:
  • Meal coverage (prandial insulin)
  • Correction of hyperglycemia
• Observational studies show that CSII is associated with reduced severe hyperglycemic events (>300 mg/dL) and hypoglycemic events (<50 mg/dL) in hospitalized patients 1

Timing of Bolus Administration

• For rapid-acting insulin boluses:
  • Administer 15 minutes before meals for optimal postprandial glucose control 2, 3
  • If not possible, administering immediately before meals is better than after meals 3
• For high-fat or high-protein meals, extended boluses may be more effective 2

Types of Bolus Options with Insulin Pumps

1. Standard bolus: Entire insulin dose delivered at once
2. Extended bolus: Insulin dose delivered over a prolonged period
3. Dual-wave/combo bolus: Combination of immediate and extended delivery
4. Super bolus: Temporarily reducing basal rate and adding this insulin to bolus 4, 5

Special Considerations

Intravenous Insulin Administration

• When using IV insulin, boluses can be administered within the infusion protocol 6
• FDA guidance for IV insulin states:
  • Can be used at concentrations from 0.1 unit/mL to 1 unit/mL
  • Must be administered under medical supervision with close monitoring of blood glucose and potassium levels 6

Transitioning Between Delivery Methods

• When transitioning from IV to subcutaneous insulin:
  • Administer basal insulin immediately after stopping IV infusion
  • Give the first bolus of rapid-acting insulin with the first meal 2
  • Follow a transition protocol to reduce morbidity and costs 1

Automated Insulin Delivery Systems

• Modern systems integrate insulin pumps with continuous glucose monitoring and algorithms 1
• These systems can automatically adjust basal rates but still require manual boluses for meals 1
• Threshold suspend features may need to be turned off in hospital settings 1

Potential Pitfalls and Safety Considerations

1. Risk of hypoglycemia:

   • Consider insulin on board (active insulin) when calculating correction boluses 2
   • Avoid prolonged use of correction insulin without basal insulin 1

2. Timing issues:

   • Mismatched timing between insulin action and meal absorption can lead to post-meal hyperglycemia or delayed hypoglycemia 7
   • Bolus given after meals results in significantly higher 1-hour postprandial glucose levels 3

3. Device-related concerns:

   • Hospital policies should address potential safety issues with insulin pumps (software problems, alarm errors, site infections) 1
   • Ensure proper staff training for managing diabetes technology in hospital settings 1

By properly coordinating basal insulin infusion with appropriately timed and calculated bolus doses, optimal glycemic control can be achieved while minimizing the risk of hypoglycemia.