Initial Dosing of Rapid-Acting (Prandial) Insulin
Start with 4 units per day OR 10% of the basal insulin dose, administered with the largest meal or the meal causing the greatest postprandial glucose excursion. 1
Starting Dose Recommendations
The most recent American Diabetes Association guidelines (2025) provide clear dosing parameters for initiating rapid-acting insulin:
- 4 units per day as a flat starting dose 1
- OR 10% of the current basal insulin dose 1
- Administer with the largest meal or the meal with the greatest postprandial glucose excursion 1
Titration Strategy
Once initiated, adjust the dose systematically:
- Increase by 1-2 units or 10-15% of the current dose twice weekly based on glucose readings 1
- If A1C is <8% (<64 mmol/mol) when starting prandial insulin, consider lowering the basal insulin dose by 4 units per day or 10% to prevent hypoglycemia 1
- For hypoglycemia: determine the cause; if no clear reason exists, lower the corresponding dose by 10-20% 1
Clinical Context for Initiation
Prandial insulin should be added when:
- Basal insulin has been titrated to acceptable fasting glucose levels but A1C remains above goal 1
- Basal insulin dose exceeds 0.5 units/kg/day with signs of overbasalization 1
- There is an elevated bedtime-to-morning or postprandial-to-preprandial glucose differential 1
Important Caveats
Do not use rapid-acting insulin at bedtime in older adults or those at risk for nocturnal hypoglycemia 1. The timing should be immediately before meals to match the rapid onset of action with carbohydrate absorption 1.
For patients requiring simplification, if the prandial insulin dose is ≤10 units per dose, consider discontinuing it and adding non-insulin agents instead 1. If >10 units per dose, decrease by 50% and add non-insulin agents 1.
Monitoring Requirements
Self-monitoring of blood glucose is essential for safe insulin titration and should be performed before each meal and at bedtime 1. Adjustments should be made every 1-4 weeks based on glucose patterns 2. The goal is premeal glucose of 90-150 mg/dL (5.0-8.3 mmol/L), though this may be adjusted based on individual health status and goals of care 1.