Humalog Onset of Action
Humalog (insulin lispro) begins working within 15 minutes of subcutaneous injection, peaks at 30-90 minutes, and has a duration of action of less than 5 hours. 1
Pharmacokinetic Profile
Rapid Onset and Peak:
- Onset of action occurs within 15 minutes of subcutaneous administration 1
- Peak insulin levels are reached at 30-90 minutes after injection 1
- Duration of activity is less than 5 hours, making it significantly shorter than regular human insulin 1
The American Diabetes Association recognizes that rapid-acting insulin analogs like Humalog (insulin lispro) are preferred for mealtime insulin dosing due to their quick onset of action 2
Comparison to Regular Human Insulin
Key Pharmacokinetic Advantages:
- Humalog has a faster subcutaneous absorption compared to regular human insulin 1
- It produces an earlier and greater insulin peak than regular insulin 1
- The more rapid postpeak decrease allows better matching of insulin action to meal absorption 1
Regular human insulin, by contrast, has an onset of 15 minutes but peaks much later at 3-4 hours and has a duration of 6-8 hours 2
Clinical Implications for Timing
Practical Administration Guidelines:
- Humalog should be injected within 15 minutes before meals, not 30-40 minutes like regular human insulin 3
- It can even be administered immediately before or after meals when food intake is unpredictable 4
- This flexible timing improves patient quality of life and adherence 4
The molecular basis for this rapid action is that insulin lispro has lysine and proline reversed at positions B28 and B29, which weakens self-association into hexamers and allows faster absorption into the circulation 5, 3
Clinical Benefits
Postprandial Glucose Control:
- Better control of postprandial hyperglycemia compared to regular human insulin 6
- Smaller postprandial rise in blood glucose 3
- Reduced risk of delayed hypoglycemia, especially at night 6, 3
The time-action profile of Humalog mimics the physiological response of endogenous human insulin to food intake more closely than regular insulin 4
Common Pitfall to Avoid
Do not inject Humalog 30 minutes before meals as you would with regular human insulin—this timing is unnecessary and increases the risk of pre-meal hypoglycemia. The rapid onset allows injection within 15 minutes of eating 3, 1