Types of Insulin for Type 1 Diabetes

Human Insulin and Insulin Analogs are available for insulin replacement therapy. Insulins also are classified by the timing of their action in your body – specifically, how quickly they start to act, when they have a maximal effect and how long they act. Insulin analogs have been developed because of limitations with human insulins such as slow and unpredictable absorption.
 
Insulin analogs which have largely replaced the use of human insulin, have a more predictable duration of action. The rapid acting insulin analogs work more quickly, and the long acting insulin analogs last longer and have a more even, "peakless or flat" effect.
 
Insulin has been available since 1921. It was initially extracted from beef and pork pancreases. In the early 1980’s, technology became available to produce human insulin synthetically. Synthetic human insulin has replaced beef and pork insulin in the US. And now, insulin analogs are replacing human insulin.
 
Insulins are categorized by differences in:
  • Onset: How quickly they act.
  • Peak: How long it takes to achieve maximum impact.
  • Duration: How long they last before they wear off.
  • Concentration Insulins sold in the U.S. have a concentration of 100 units per ml or U-100, more concentrated options are also available though less commonly used.  Be sure to pay close attention to the concentration for use with insulin pump as they do not adjust for more concentrated insulin.
  • Route of delivery: whether they are injected under the skin, inhaled or given intravenously.

Insulin is usually injected into the fatty tissue just under the skin. This is also called subcutaneous tissue. See a table of insulin action below and a graphic illustration of onset of action, peak effect and duration of action of the different insulins.

Types of insulin:

There are three main groups of insulins: Fast-acting, Intermediate-acting and Long-acting insulin.

1. Fast-acting insulin is absorbed quickly from your fat tissue (subcutaneous) into the bloodstream and is used to control blood glucose during meals and snacks and to correct high blood glucose. These include: insulin aspart, insulin lispro, insulin glulisine and regular human insulin.

2. Intermediate-acting insulin, NPH human insulin, is absorbed more slowly, and lasts longer and used to control the blood glucose overnight, while fasting and between meals. 

3. Long acting insulin analogs, insulin glargine, and insulin degludec have an onset of insulin effect in 1 1/2 - 2 hours. The insulin effect plateaus over the next few hours and is followed by a relatively flat duration of action that lasts 12-24 hours for insulin detemir, 24 hours for insulin glargine and 42 hours for insulin degludec.

Compare insulin actions here:

Type of Insulin Onset Peak (dose dependent) Duration (dose dependent) Appearance
Fast-acting        
fiasp/lispro - aabc <5 1-2 hr. 3-4 hr clear
lispro/aspart/glulisine <15 min. 1-2 hr. 4-6 hr. clear
regular ½-1 hr. 2-4 hr. 6-8 hr. clear
Intermediate-acting        
NPH 1-2 hr. 6-10 hr. 12+ hr. cloudy
Long-acting        
glargine 1.5 hr. Flat, Max effect in 5 hrs. 12-24 hr. clear
degludec 1 -2 hr. Flat 42 hr. clear

Graph illustrating the time action curves of different insulins

Activity Profiles of Different Types of Insulin