How Do the Different Types of Insulin Work?

All types of insulin are useful in treating diabetes, although they have different characteristics for various situations. Learn more.
How Do the Different Types of Insulin Work?

Last update: 09 February, 2023

Diabetes is a disease in which the body doesn’t produce enough insulin or the tissues develop resistance to it. One of the available treatments is the administration of the hormone necessary to regulate blood glucose levels. Today, there are different types of insulin that are adapted to the needs of each patient. This is a hormone synthesized by the beta cells of the pancreas, which introduces glucose from the bloodstream to the different tissues. The cells will use this substance as their main source of energy.

All patients with type 1 diabetes must take insulin, while in type 2 diabetes, it’s only used when the other treatments don’t produce the desired effect. In this regard, the different types of insulin have unique characteristics and aren’t interchangeable with one another.

Insulin characteristics

Sugar in the blood.
Although it’s a hormone produced by the human body and circulates in the blood, it’s produced artificially in laboratories.

Generally speaking, insulin is a hormone that’s injected into areas with abundant adipose tissue such as the abdomen or into areas with large muscles such as the leg. These areas facilitate its entry into the bloodstream, so it can exert its action more quickly and efficiently.

The types of insulin available have their own characteristics that allow them to be differentiated from one another, which are the onset time, the maximum point, and the duration. The onset time refers to how quickly the drug will start working, that is, how long it takes to lower your blood glucose levels.

On the other hand, the peak is the moment when insulin reaches its maximum strength, while the duration is the time during which the drug acts to lower blood sugar levels. Knowing all these terms is essential in order to know how each type of insulin works in the body.

It’s important to note that these characteristics can vary from one brand of insulin to another, even when they’re within the same group. So, medical advice is essential in the treatment of the disease, regardless of the type of diabetes suffered.

Types of insulin

Despite the differences, all of them usually have the same presentation in 100 milliliter bottles or in 3 milliliter cartridges to be administered in pens. The most common concentration is 100 units of insulin per milliliter, although presentations of 500 units per milliliter can also be found for the most severe cases.

One of the main characteristics that differentiates the types of insulin is the onset time and the duration of the effect. In this regard, insulin can be divided into 4 different groups according to its action, which are the following:

Fast or ultra-fast-acting insulin

This is an insulin analog that underwent a modification in its structure, which allows it to have the fastest absorption of all. The onset time is usually less than 15 minutes after the injection, so it’s usually administered just before a meal.

The maximum point is reached between 30 minutes and 1 hour after its administration. However, the duration of the effect is very short, which can vary between 2 and 4 hours. The brand names of the fast-acting insulins currently available are Apidra, HumaLog, and NovoLog.

Regular or short-acting insulin

Also known as crystalline insulin due to its similarity to water, it’s a type of insulin to which no type of retardant substance was added. In this regard, it will reach the bloodstream 30 minutes after its application, so studies recommend injecting it between 30 and 45 minutes before meals.

The maximum effect is achieved after 1 or 3 hours and lasts for up to 6 hours. It doesn’t usually cause adverse effects, although there’s a risk of developing postprandial hypoglycemia.

This type of insulin can be administered intravenously, so it would act immediately. The commercial insulins belonging to this group are Humulin R and Novolin R.

Intermediate-acting insulin

This group of insulin is known as Neutral Protamine Hagedorn or NPH. It’s a crystalline insulin to which a protein called protamine was added in order to delay its absorption and prolong the duration of its effect. Its appearance is cloudy and milky, and it’s also necessary to rub it between your hands before applying it.

The absorption of NPH insulin is slow and takes 2 to 4 hours to start working. It reaches a peak between 4 and 12 hours after its administration and its effect can last for up to 18 hours. However, studies show that it can have intra-individual variations, so its effect is unpredictable in up to 50% of cases.

In general terms, it’s best to administer this insulin between 30 and 45 minutes before food, with a maximum frequency of 2 daily doses. The currently available NPH insulins are Humulin N and Novolin N.

Long-acting and ultra-long-acting insulin

A woman holding carrots and beats.
Treatment with any type of insulin must be supplemented with lifestyle changes, such as following a healthy diet.

Generally speaking, these types of insulin are very slowly absorbed, don’t have peaks, and last between 24 and 36 hours. Long-acting insulin has alterations in its structure that delay its absorption and modify other characteristics, so it shouldn’t be administered in the same syringe as other types of insulin.

This is one of the newer types of insulin and allows you to reduce the basal dose of insulin delivered. It has a transparent appearance, so it shouldn’t be confused with rapid-acting insulin. At present, there’s no fixed schedule of administration with regard to food, as it will regulate glucose levels throughout the day.

Long-acting insulin is often used in combination with fast-acting and regular-acting insulin when needed. In addition, it’s important to apply it every day at the same time, especially when used with oral hypoglycemic agents. The brand names for these insulins are Levemir and Lantus.

Premixed insulin

This type of insulin can be useful for those who find it difficult to extract the contents of two different bottles at adequate doses. It’s a fixed combination of fast-acting and intermediate-acting insulin, which is given before breakfast and dinner.

Premixed insulins are ideal for patients with vision problems or when the disease has been stabilized with a specific combination. The disadvantage presented is their little flexibility, as they don’t adjust to changes in activities or variations in the food consumed.

Inhaled insulin

This is a special type of fast-acting insulin, which has an onset time of less than 10 minutes thanks to its route of administration. The peak and duration of effect are similar to those for subcutaneously administered insulin.

It’s recommended for type-2 diabetics who don’t respond to treatment with oral hypoglycemic agents. It’s also useful in people with type 1 diabetes in combination with intermediate or long-acting insulin.

It’s always important to follow the medical indications

All types of insulin are useful in treating diabetes. However, they have different characteristics to suit various situations. In this regard, it’s important to follow all the indications provided by the specialist, from the dose to be used to the time of administration, in order to obtain the best results.

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