Insulin Lispro PRN Dosing Frequency
Insulin lispro should be administered immediately before meals (within 15 minutes or less) for prandial glucose control, typically 3 times daily with main meals, with additional correction doses as needed based on blood glucose monitoring. 1
Standard Prandial Dosing Schedule
- Administer lispro 15 minutes or less before each meal (breakfast, lunch, and dinner) as the rapid-acting insulin component of a basal-bolus regimen 1
- The rapid onset of action (5 minutes) and peak effect (1-2 hours) make immediate pre-meal timing essential to match postprandial glucose excursions 1
- Duration of action is 3-4 hours, which is shorter than regular human insulin 1
Initial Dosing Parameters
- Start with 4 units per meal or 0.1 units/kg per meal as the initial mealtime lispro dose 1
- When adding prandial insulin to existing basal therapy, consider decreasing the basal insulin dose by the same amount as the starting mealtime dose 1
- Total daily insulin requirements for type 2 diabetes patients are generally ≥1 unit/kg due to insulin resistance 2
PRN Correction Doses
- Additional supplemental doses can be given based on postprandial glucose levels to improve blood glucose management without additional hypoglycemia or weight gain 2
- Adjust both basal and prandial insulin doses based on self-monitoring of blood glucose levels 1
- Target postprandial glucose <180 mg/dL 3
Timing Considerations
- Lispro must be given immediately before meals (not 30-45 minutes prior like regular insulin) due to its rapid pharmacokinetics 4, 5
- The very rapid subcutaneous absorption creates an increased potential for hypoglycemia if carbohydrate intake is delayed or reduced 6
- Patients injecting lispro closer to mealtime achieve lower postprandial glucose levels compared to regular human insulin given 30 minutes before meals 4
Common Pitfalls to Avoid
- Do not delay meal consumption after lispro injection - the rapid onset (5 minutes) means hypoglycemia can develop quickly if food intake is postponed 1, 6
- Meal carbohydrate content is a critical determinant - hypoglycemia develops more frequently and rapidly with lispro in settings of reduced carbohydrate intake 6
- Patients switching from regular insulin to lispro should monitor glucose levels frequently and may need adjustments in carbohydrate intake and/or lispro dosage 6
- Evening dose optimization may be needed - consider reducing evening premeal lispro by 20% and increasing bedtime basal NPH by 25% to prevent nocturnal hyperglycemia while maintaining postprandial control 7
Monitoring Requirements
- Check both fasting and postprandial glucose to guide dose adjustments 3
- More frequent monitoring is recommended during periods of stress or illness 3
- If hypoglycemia occurs, identify the timing and reduce the corresponding insulin dose 3
- Treat hypoglycemia with 15-20g of fast-acting carbohydrates and recheck after 15 minutes 3