What is the typical starting dose of mealtime insulin, such as aspart (novolog) or lispro (humalog), for a patient with diabetes?

Starting Dose of Mealtime Insulin

The recommended starting dose of mealtime insulin (aspart or lispro) is 4 units per meal, 0.1 units/kg per meal, or 10% of the basal insulin dose per meal if the HbA1c is less than 8%. 1

Initial Dosing Algorithm

When adding prandial insulin to an existing basal insulin regimen, use the following approach:

• Start with 4 units per meal as the standard initial dose 1
• Alternative calculation: 0.1 units/kg body weight per meal 1
• Alternative calculation: 10% of the current basal insulin dose per meal 1
• Consider decreasing the basal insulin dose by the same amount as the starting mealtime dose to prevent hypoglycemia 1

When to Initiate Mealtime Insulin

Add prandial insulin when:

• Basal insulin has been titrated to acceptable fasting blood glucose levels but HbA1c remains above target 1
• Basal insulin dose exceeds 0.5 units/kg per day and glycemic goals are not met 1
• Evidence of "overbasalization" exists (elevated bedtime-to-morning or postprandial-to-preprandial glucose differentials) 1

Starting Strategy

Begin with a single injection before the largest meal or the meal with the greatest postprandial glucose excursion 1. This simplified approach:

• Reduces injection burden initially 1
• Allows assessment of patient tolerance and response 1
• Can be expanded to additional meals if HbA1c targets are not met 1

Dose Adjustments Based on HbA1c

The starting dose should be modified based on baseline glycemic control:

• If HbA1c <8%: Use standard starting doses (4 units, 0.1 units/kg, or 10% of basal) 1
• If HbA1c <8%: Consider lowering the basal insulin dose by 4 units per day or 10% when adding prandial insulin 1
• Higher HbA1c levels: May require more aggressive initial dosing, but the guidelines prioritize safety with conservative starting doses 1

Titration Protocol

After initiation:

• Increase by 1-2 units or 10-15% of the current dose based on pre-meal and postprandial glucose readings 1
• Titrate each meal's insulin dose independently based on the corresponding postprandial glucose values 1
• For hypoglycemia without clear cause, lower the corresponding dose by 10-20% 1

Medication Management

When initiating mealtime insulin:

• Continue metformin in most cases 1
• Discontinue sulfonylureas to reduce hypoglycemia risk 1
• Discontinue DPP-4 inhibitors as they become redundant with prandial insulin 1
• Consider discontinuing GLP-1 receptor agonists when advancing to full basal-bolus regimens, though they may be continued with simpler regimens 1

Critical Timing Considerations

Rapid-acting insulin analogues (aspart, lispro, glulisine) should be injected 0-5 minutes before meals 1. This timing:

• Optimizes postprandial glucose control 2
• Reduces the risk of pre-meal hypoglycemia compared to regular human insulin 2
• Provides flexibility for patients with unpredictable meal timing 3

Common Pitfalls to Avoid

• Do not delay insulin intensification when basal insulin alone is insufficient—this leads to prolonged hyperglycemia and increased complication risk 1
• Avoid using only correction (sliding scale) insulin without scheduled mealtime doses, as this is reactive rather than proactive 4
• Do not continue aggressive basal insulin titration beyond 0.5 units/kg per day without adding prandial coverage—this increases hypoglycemia risk without improving postprandial control 1
• Ensure patient education on carbohydrate counting and dose adjustment before initiating mealtime insulin to optimize safety and efficacy 1

Alternative Approach: Premixed Insulin

If simplicity is prioritized over flexibility:

• Start with 10 units or 0.1-0.2 units/kg per day divided into two equal doses before breakfast and dinner 5
• This approach is less flexible but reduces injection frequency 5
• Requires more consistent meal timing and carbohydrate content 1