Time-action of different insulins


Starts working


Stops working


Humalog® (lispro)

NovoLog® (aspart)

Apidra® (glulisine)

5 to 15 minutes

1 to 2 hours

2 to 4 hours


Regular (R)

30 to 45 minutes

3 hours

4 to 8 hours



2 to 4 hours

4 to 8 hours

10 to 16 hours


Intermediate-acting/rapid acting

NPH and regular insulin

5 to 15 minutes

30 to 45 minutes

1 to 2 hours/ some increase at 4 to 8 hours

2 to 3 hours/

4 to 8 hours

10 to 16 hours

10 to 16 hours


Lantus® ( glargine)

Levemir® ( detemir)

2 hours

No peak

24 hours

*The long-acting insulin may work the best between four and eight hours.

**Lantus and Levemir cannot be mixed with any other insulin.

How to help insulin work best

  • Take your insulin at the same time each day as directed.
  • Take your insulin every day, even if you feel sick. If you cannot eat normally because you are sick, see Sick day tips when taking insulin.
  • Don't change your meal plan, exercise, prescribed medications or insulin routines without talking to your health care provider.

Pen devices

Most insulins are available in a pre-filled pen you throw away after use. See the product insert for specific use guidelines.

Source: Allina Health's Patient Education Department, Gestational Diabetes: When You Have Diabetes During Pregnancy, third edition, ISBN 1-931876-21-6
Reviewed By: Reviewed by Allina Health's Patient Education Department experts
First Published: 11/27/2006
Last Reviewed: 01/20/2014

The insulin you inject only lowers your blood glucose. It does not cross the placenta to your baby.