When to adjust prandial (related to a meal) insulin dose and correction insulin dose?

Adjusting Prandial and Correction Insulin Doses

Prandial and correction insulin doses should be adjusted based on blood glucose patterns observed over 3-7 days, with incremental changes of 10-15% when glucose values consistently fall outside target ranges. 1

Prandial Insulin Adjustment Algorithm

When to Adjust Prandial Insulin

• Adjust when >50% of post-meal glucose readings over 1 week are above target (typically 90-150 mg/dL) 1, 2
• Evaluate patterns by meal (breakfast, lunch, dinner) separately
• Consider adjustment when A1C remains elevated despite controlled fasting glucose

How to Adjust Prandial Insulin

1. Increase dose by 10-15% (or 1-2 units for smaller doses) if post-meal glucose consistently exceeds target 1
2. Decrease dose by 10-15% (or 1-2 units) if hypoglycemia occurs (<70 mg/dL) or >2 readings/week are <90 mg/dL 1
3. Reassess every 1-4 weeks for safety and efficacy 3, 4

Special Considerations for Prandial Insulin

• For high-carbohydrate meals: Consider insulin-to-carbohydrate ratio adjustments (typically 1 unit per 10-15g carbs) 5
• For high-fat/protein meals: May need additional 1-2 units to account for delayed glucose rise 1
• For exercise: Reduce prandial dose by 25-50% if exercise will occur within 2 hours after meal 1

Correction Insulin Adjustment Algorithm

When to Adjust Correction Factor

• When >50% of correction doses fail to bring glucose to target range within 2-4 hours
• When correction doses frequently cause hypoglycemia

How to Adjust Correction Factor

1. Calculate current correction factor: 1800 ÷ Total Daily Insulin = mg/dL lowered by 1 unit
2. Increase correction dose (make correction factor smaller) if glucose remains elevated after correction
3. Decrease correction dose (make correction factor larger) if hypoglycemia occurs after correction
4. Standard starting correction factors:
   • Insulin sensitive: 1 unit per 50 mg/dL above target
   • Average sensitivity: 1 unit per 25-30 mg/dL above target
   • Insulin resistant: 1 unit per 15-20 mg/dL above target 1

Monitoring and Documentation

• Document blood glucose before meals and at bedtime daily during adjustment periods 1
• Consider occasional 3 AM readings to detect nocturnal hypoglycemia 2
• Review patterns after 3-7 days before making further adjustments 2
• For patients using continuous glucose monitoring (CGM), evaluate time-in-range metrics and glucose trends 1

Common Pitfalls to Avoid

• Overbasalization: Increasing basal insulin when the problem is inadequate prandial coverage 2
• Stacking insulin: Administering correction doses too frequently (less than 4 hours apart) 1
• Ignoring patterns: Making adjustments based on single glucose readings rather than consistent patterns 3, 4
• Therapeutic inertia: Delaying necessary dose adjustments despite persistent hyperglycemia 2
• Inadequate monitoring: Failing to collect sufficient data to identify clear patterns 4

Special Populations

• Older adults: Consider simplified regimens with less aggressive targets (90-150 mg/dL) and smaller adjustment increments (1-2 units) 1
• Hospitalized patients: More frequent monitoring and adjustment may be needed (every 24-48 hours) 1
• Patients on glucocorticoids: May need 40-60% higher prandial insulin doses, especially for daytime meals 1

By following this systematic approach to insulin adjustment based on glucose patterns, you can optimize glycemic control while minimizing hypoglycemia risk, ultimately improving morbidity and mortality outcomes for patients requiring insulin therapy.