How do you initiate mealtime insulin therapy?

Initiating Mealtime Insulin Therapy

To start mealtime insulin, begin with 4 units or 10% of the basal insulin dose at the largest meal, then titrate based on blood glucose monitoring. 1

Initial Dosing Strategy

Mealtime insulin (also called prandial or bolus insulin) should be initiated when basal insulin alone is insufficient to achieve glycemic targets. Here's how to start:

• Starting dose: 4 units or 10% of the basal insulin dose at each meal, or start with just the largest meal first 1
• Timing: Administer rapid-acting insulin analogs (lispro, aspart, glulisine) immediately before meals 1
• Insulin type: Use rapid-acting insulin analogs rather than regular human insulin for better postprandial control 1
• Administration site: Inject subcutaneously into abdomen, thigh, or deltoid, rotating sites to prevent lipodystrophy 2

Dose Titration Algorithm

Adjust each meal dose separately based on 2-hour postprandial glucose (PPG) patterns:

• PPG >200 mg/dL: Increase by 2-4 units
• PPG 150-200 mg/dL: Increase by 1-2 units
• PPG 100-150 mg/dL: No change
• PPG <100 mg/dL: Decrease by 1-2 units
• Any hypoglycemia: Decrease corresponding meal dose by 10-20% 3

Carbohydrate Counting Approach

For patients capable of more advanced management:

1. Learn carbohydrate counting to match insulin to carbohydrate intake 1
2. Establish an insulin-to-carbohydrate ratio (typically starting at 1 unit per 10-15g carbohydrate)
3. Calculate mealtime dose based on carbohydrate content of the meal

Practical Considerations

• Meal timing: With rapid-acting analogs, meals can be consumed at different times, offering flexibility 1
• Physical activity: If exercise occurs within 1-2 hours after injection, reduce mealtime insulin dose to prevent hypoglycemia 1
• Hypoglycemia management: Always carry quick-acting carbohydrates (glucose tablets, juice) to treat hypoglycemia 1
• Monitoring: Check blood glucose before meals and 2 hours after to assess effectiveness of mealtime insulin

Progressive Intensification

If glycemic targets aren't met with basal plus one mealtime injection:

1. Add mealtime insulin to additional meals (basal-bolus approach)
2. Consider switching to premixed insulin twice daily if adherence is an issue 1
3. For patients requiring large insulin doses, consider adding thiazolidinediones or SGLT2 inhibitors to improve control and reduce insulin requirements 1

Common Pitfalls to Avoid

• Delayed injection: Unlike regular insulin (which should be given 30-45 minutes before meals), rapid-acting analogs work best when given immediately before eating 4, 5
• Fixed insulin with variable meals: Without carbohydrate counting, inconsistent carbohydrate intake leads to glucose variability
• Skipping meals: Avoid skipping meals after taking mealtime insulin to prevent hypoglycemia 1
• Inadequate monitoring: Failure to check postprandial glucose levels makes proper dose adjustment impossible
• Forgetting to adjust for exercise: Physical activity can significantly lower blood glucose when performed after mealtime insulin administration 1

By following this structured approach to initiating and titrating mealtime insulin, you can effectively improve postprandial glucose control while minimizing the risk of hypoglycemia.