We all known that people with diabetes need insulin treatment. But what is insulin and why it is so important for our body function? We will explain everything you need to know about insulin in this post.

What is insulin?

Insulin is a hormone produced by the pancreas which helps regulating the blood glucose levels. This hormone is essential to transport and store glucose in the cells, helping using glucose as an energy source for the organism.

Insulin acts as a key to let the glucose access the cells. If glucose cannot enter into the cells, it accumulates in the blood.

Pancreas produces insulin of two kinds:

  • Slow and continuous insulin that helps blood glucose levels to remain always stable between 70-100 mg/dl, known as basal insulin secretion.
  • Bolus insulin, secreted in a larger quantity, generally when the blood glucose increases after meals, known as pulsatile insulin secretion.

Types of injected insulin

Depending on the type of injected insulin you use, the starting time of its effect (when it helps lowering the blood sugar level) may vary.

Moreover, it is necessary to know the peak when insulin reaches its maximum effect: this is the moment in which blood glucose levels will start descending.

We should also be conscious about the duration of the insulin effects, the amount of time during which the blood glucose level will keep lowering.

Insulin can be therefore classified into several groups:

Fast-acting insulin

It is rapidly absorbed from adipose (subcutaneous) tissue in the bloodstream. It is used to control blood glucose during the ingestion of food or drinks, and corrects the high blood sugar levels.

Start 10 – 15 minutes
Peak 30 – 90 minutes
Duration 3 – 5 hours


Examples: Apidra, Humalog, Novorapid, etc.


Short-acting or regular insulin

As the name suggests, these are short-acting insulins and usually take longer to produce an effect.

Start 30 – 60 minutes
Peak 2 – 3 hours
Duration 5 – 7 hours

Example: Actrapid.

Intermediate acting insulin

This type of insulin acts like basal insulin: it is absorbed slower, extending the duration of its effect. It is dispensed once or twice a day and it is specially used to control the blood glucose level during the night, while fasting or between meals. It is usually combined with fast-acting insulins.

Start 1 – 2 hours
Peak 4 – 7 hours
Duration 10 – 13 hours

Example: Humulin N.

Long-acting insulin

Like intermediate-acting insulins, they are used like basal insulins and slowly absorbed, having a minimum peak effect. Its effect is more stable during most part of the day.

Start 1 – 2 hours
Peak 6 – 7 hours
Duration 24 – 36 hours

Examples: Tresiba, Toujeo, Levemir, Lantus.

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Premixed Insulins

These are combinations of fast-acting insulins with intermediate-acting insulins, in different proportions. Just an injection of premixed insulin is enough to control both basal and prandial glycemia.

Why insulin needs to be injected?

Diabetes management would be much easier if insulin could be taken by pills, we all agree with that. However, it is not possible to take insulin as pills because it would decompose during the digestion. That is why it has to be injected into the fat located under the skin so that it can be added to the blood.

If you want more information about how to inject insulin correctly, click on the following link. Moreover, remember that our device Insulclock works with all the mentioned insulin pens and that it can definitely help you on your diabetes treatment with insulin.

Inyección de insulina