How to add short-acting (rapid-acting) insulin?

Adding Short-Acting (Rapid-Acting) Insulin to Treatment Regimen

Short-acting (rapid-acting) insulin should be added before meals to control postprandial glucose excursions, with dosing based on carbohydrate content, pre-meal glucose levels, and anticipated physical activity. 1

When to Add Short-Acting Insulin

• Add rapid-acting insulin when basal insulin has been titrated to an acceptable fasting blood glucose level but HbA1c remains above target 1
• Consider adding when postprandial glucose excursions are significant despite optimized basal insulin 1
• Start with a single injection of rapid-acting insulin (lispro, aspart, or glulisine) before the largest meal of the day 1

Dosing Recommendations

• Initial dosing:

  • Start with 2-4 units before meals 1
  • For more precise dosing, calculate 0.1 units/kg per meal or 10% of total daily basal dose 2
  • Adjust based on pre-meal glucose levels and carbohydrate content of meals 3

• Titration:

  • Increase dose by 1-2 units every 3 days until target postprandial glucose is achieved 2
  • Target postprandial glucose: 90-150 mg/dL (5.0-8.3 mmol/L) 1
  • If hypoglycemia occurs, reduce dose by 10-20% 4

Administration Timing

• Administer rapid-acting insulin 0-15 minutes before meals 3
• Unlike regular human insulin, which requires injection 30-45 minutes before meals, rapid-acting analogues can be injected immediately before eating 5, 6
• For high-fat meals, consider injecting during or immediately after the meal to better match insulin action with delayed nutrient absorption 3

Choosing Between Rapid-Acting Insulin Options

• Available options include insulin lispro (Humalog), insulin aspart (NovoLog/NovoRapid), and insulin glulisine (Apidra) 1
• Newer ultra-rapid formulations like faster-acting insulin aspart (Fiasp) and ultra-rapid insulin lispro (Lyumjev) have even quicker onset 7
• Lyumjev has shown improved postprandial glucose control compared to standard lispro, with significant reductions in postprandial glucose excursions 7

Monitoring and Adjustment

• Check blood glucose before meals and 2 hours after meals to assess effectiveness 2
• Monitor for hypoglycemia, especially between meals 8, 5
• Adjust insulin-to-carbohydrate ratios based on postprandial glucose patterns 1
• For persistent hyperglycemia, consider progressing to multiple pre-meal injections 1

Special Considerations

• Always check insulin labels before administration to avoid medication errors 3
• Do not mix rapid-acting insulin with any other insulin or liquid when used in a pump 3
• When using insulin pumps, change infusion sets every 3 days and replace insulin in the reservoir at least every 7 days 3
• For patients with steroid-induced hyperglycemia, NPH insulin may be more appropriate than rapid-acting insulin due to its intermediate-acting profile 4

Progression of Therapy

• If a single pre-meal injection is insufficient, progress to multiple pre-meal injections (basal-bolus regimen) 1
• Consider alternative approaches if multiple daily injections are challenging:
  • Fixed-ratio premixed insulins (e.g., 70/30,75/25, or 50/50 mixes) 1
  • Basal insulin plus GLP-1 receptor agonist 1

Common Pitfalls to Avoid

• Avoid using rapid-acting insulin at bedtime without food intake 2
• Do not use sliding scale insulin as the sole method of glucose control 2
• Avoid delaying meals after administering rapid-acting insulin 5
• Remember that rapid-acting insulin has a shorter duration of action than regular human insulin, reducing the risk of late postprandial hypoglycemia 9, 8