What types of insulin are there and how do they act?

tipos de insulinas y cómo actúan0

The pancreas of a person without diabetes secretes an amount of insulin continuously throughout the day and, additionally, after each meal, a larger amount to metabolise the carbs consumed. These two components are substituted by long-acting or intermediate-acting insulins and fast-acting insulins, respectively. Additionally, there are premixed insulins that include both fast-acting and intermediate-acting insulin in the same device.

Here are the types of insulin that are on the market, as well as factors that can affect their action:

Intermediate-acting insulin

It is known as NPH insulin: it lasts around 10-13 hours, its action peaks between 4-7 hours and becomes active after 1-2 hours. It has a milky appearance. Its activity is very variable from one day to the next, with a risk of hypoglycaemias (low blood sugar) due to its action peak and, so that it covers 24 hours, it must be administered in 2 or 3 daily doses.


Long-acting insulin

Insulin glargine U100 (Lantus®): has a half-life of 20-hours, starts acting in 1-2 hours and does not have a pronounced activity peak, which reduces the risk of hypoglycaemias with regard to NPH insulin. It is normally administered in a single daily dose. Less variability than NPH insulin. Insulin glargine U300 (Toujeo®) is a new version of the U100, with a greater concentration that makes it last longer, with a half-life of 24 hours and less hypoglycaemias with less variability.

Insulin Detemir (Levemir®): has a half-life of 12-16-hours, starts acting in 1-2 hours and does not have a pronounced activity peak, which reduces the risk of hypoglycaemias with regard to NPH insulin. It normally requires being administered twice a day to cover 24 hours. It also shows less variability than NPH insulin.

Insulin Degludec (Tresiba®): has a half-life of more than 24 hours, which ensures daily coverage with a single injection with regard to NPH insulin.

Fast-acting insulin

Ultra-fast-acting insulins: we currently have access to Lispro (Humalog®), Aspart (Novorapid®) and Glulisine (Apidra®). All 3 of them have similar characteristics: they become active in 10-15 minutes after the injection, their activity peak is after 30-90 minutes and they last between 3 to 4 hours.

Regular insulin (Actrapid®) is less physiological, that is, it emulates insulin secretion by the pancreas poorly. It becomes active 30-60 minutes after the injection. Its activity peak is after 2-3 hours and lasts 5-7 hours.

Faster Aspart (Fiasp®): it becomes active twice as quickly, which leads to a an earlier drop in glucose compared to Aspart insulin (which allows for better control of glucose after a meal in the first two hours). Its duration is similar and it peaks 1 to 3 hours after being injected. It seems that insulin pump users will probably gain more advantages from this new insulin.





Pre-mixed insulins

There are several pre-established insulin mixes on the market, akin to fast or regular-acting and intermediate-acting insulin. The disadvantage is that the percentage of each type of insulin is pre-set and the insulins cannot be modified individually.


Factors that modify insulin action 

The following advance the action of insulin:
Physical exercise of the area that has been injected.
Heat on the injection area.
A massage on the area injected with insulin.
If the injection is too deep, because the insulin could be injected into the muscle.
Injection on abdomen and arms.
Very small doses.


The following delay the action of insulin:
Cold on the injection area.
If the injection is too superficial.
Injection on areas with lipohypertrophy. It does not only delay absorption, but also makes it more erratic and less reliable.
Injection on buttocks or thighs.

Written by Dr Cintia González Blanco, Consultant 1 Endocrinology and Nutrition Service at Hospital de Sant Pau, Associate Professor at UAB and member of CIBER-BBN, Coordinator of the 2.0 diabetes group and member of the SED technologies applied to diabetes group; she is part of the editorial committee at SocialDiabetes.



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