Which has a greater effect on glucose reduction, Lispro (insulin lispro) or Aspart (insulin aspart)?

Insulin Lispro and Aspart Have Equivalent Effects on Glucose Reduction

Both insulin lispro and insulin aspart have equivalent effects on glucose reduction, with no clinically significant differences in their ability to lower blood glucose levels.

Pharmacokinetic Comparison

The American Diabetes Association's Standards of Care in Diabetes (2024) classifies both lispro and aspart as rapid-acting insulins with similar pharmacokinetic profiles 1:

• Onset of action: 15-30 minutes
• Peak effect: 1-3 hours
• Duration of action: 3-5 hours

These properties allow both insulins to effectively control postprandial glucose excursions by mimicking physiologic insulin secretion patterns.

Direct Comparative Evidence

A direct head-to-head comparison study of insulin aspart and insulin lispro in patients with type 1 diabetes demonstrated equivalent pharmacodynamic effects 2:

• No significant differences in blood glucose excursions (0-6 hours)
• No significant differences in maximum postprandial blood glucose excursions
• Equivalent pharmacokinetic endpoints

The study concluded that "both insulin analogs are equally effective for control of postprandial blood glucose excursions" 2.

Clinical Implications

When considering which rapid-acting insulin to use:

1. Efficacy: Both insulins provide comparable glycemic control
2. Timing: Both should be administered 0-15 minutes before meals
3. Dosing: Similar dosing requirements (typically starting at 0.5 units/kg/day divided between basal and bolus)
4. Cost considerations: According to the ADA Standards of Care (2024), there are some cost differences 1:
   • Lispro U-100 vial: $30 (AWP)
   • Aspart U-100 vial: $174 (AWP)

Practical Considerations

When selecting between these insulins:

• Insurance coverage may dictate which insulin is more accessible for patients
• Delivery devices: Both are available in vials, cartridges, and prefilled pens
• Compatibility with technology: Both are suitable for insulin pump therapy

Potential Pitfalls

1. Timing errors: Both insulins require administration immediately before meals (unlike regular human insulin which needs 30-minute lead time)
2. Hypoglycemia risk: Both carry similar risks of hypoglycemia
3. Storage requirements: Both require similar storage conditions

In summary, when choosing between insulin lispro and insulin aspart, the decision should be based on factors such as cost, insurance coverage, and available delivery devices rather than differences in glucose-lowering efficacy, as both provide equivalent glycemic control.