INSULIN THERAPY: INDICATIONS AND COMPLICATIONS - MEDICINE - 2025

The insulin therapy refers to the treatment of diabetes through insulin administration produced exogenously. It was in 1921, with the discovery of insulin by Banting and Best, that insulin therapy began; the fate of diabetic patients changed radically.

Insulin is used medically to control glucose metabolism and as a treatment for diabetic ketoacidosis, one of the most feared and common complications of poorly controlled patients. Everyone with type 1 diabetes mellitus depends on insulin treatment because their pancreas does not produce the hormone.

The majority of individuals with type 2 diabetes mellitus are managed with oral hypoglycemic agents, although about 30% of them may benefit from the use of insulin, especially those who no longer respond to the usual hypoglycemic therapy or who have serious adverse reactions to it. use of such medications.

Carbohydrate metabolism is highly dependent on insulin. This hormone is anabolic; that is, it promotes the formation of proteins, triglycerides and glycogen, among others, activating the transport of cell surfaces for ions and nutrients, and modulating the action of certain enzymes that act in the main metabolic pathways.

Types of insulins

There are two major classifications of insulin accepted by the medical world: according to the duration of its effect and according to its origin.

According to the duration of its effect

Fast acting insulin

They are analogs of human insulin, created through recombinant DNA techniques. Their action begins between 5 and 15 minutes after administration and they remain active for up to 4 hours.

Its effect is most similar to that of endogenous insulin produced by the pancreas after food intake.

Medium-acting insulin

They begin to act between 1 and 2 hours after administration, and some authors describe that their effect lasts up to 16 hours.

In these variants, insulin was combined with a basic protein called protamine, which causes a delay in its absorption and, as an obvious consequence, its effect is prolonged. It is known as NPH insulin and can only be used subcutaneously.

Long-acting or slow-acting insulin

The production of this type of insulins was based on the discovery that the combination of insulin with a small amount of zinc caused the prolongation of its effect.

It begins its action 4 or 6 hours after being administered, and in some cases the duration of its activity has been described for 32 hours.

According to its origin

Animal

The first insulins used clinically in humans were of bovine, porcine, bovine origin and even some fish.

The production of insulin taken from animals was widespread for several decades, but few companies still make it today.

Biosynthetic human

They are manufactured through genetic engineering. The process consists of the insertion of human DNA into a host cell -for example, a bacterium-; By reproducing and multiplying, it produces a version that is characterized by being synthetic, in relation to human insulin.

Currently the latter is the one most used in medical practice, although highly purified ones of animal origin are still a perfectly acceptable alternative.

Mixed

Mixed insulins deserve a separate chapter. Intermediate-acting insulins (NPH) are usually mixed with regular fast-acting analogues in different proportions, according to the needs of each patient, thus seeking a rapid onset of action and a longer effect.

There are several commercial presentations of premixed insulins available in the current pharmaceutical market.

Directions to follow

In the following clinical situations, insulin is considered the treatment of choice:

- In all type 1 diabetic patients.

- In patients of any age with diabetic ketoacidosis or hyperosmolar state.

- In almost all pregnant diabetic patients.

- In type 2 diabetic patients in whom conservative treatment with dietary modifications or oral hypoglycemic agents has failed.

- In most diabetic patients under stress situations such as infections, sepsis, scheduled or emergency surgeries, prolonged treatment with steroids and abandonment of usual treatment, among others.

Insulin must be delivered into the subcutaneous tissue, into the fat just under the skin. There it remains deposited and is slowly absorbed.

Steps to follow to inject insulin

1- Clean the injection area, which must be free of abrasions, bruises or wounds. The use of alcohol and another disinfectant is not mandatory; soap and water is sufficient.

2- Lift a sheet of skin between the thumb and index finger without pinching strongly.

3- Take the syringe or pre-filled pen firmly.

4- Insert the appropriate needle completely at a 90º angle with respect to the plane of the skin.

5- Press the plunger and inject all the content corresponding to the corresponding dose.

6- Release the skin fold and withdraw the needle 10 seconds after having administered the insulin.

7- Do not rub the skin after removing the needle.

Possible complications

Insulin lipoatrophy

It consists of a loss of subcutaneous adipose tissue at the injection sites and occasionally at distant sites.

It is related to the use of poorly purified insulins of animal origin, therefore the use of highly purified or biosynthetic human ones is suggested.

Insulin lipohypertrophy

Repeated injection of insulin in the same area can cause local hypertrophy of adipose tissue due to its lipogenic effect. If this condition occurs, it is suggested to rest the affected area and rotate the injection sites.

Insulin allergy

Allergic reactions are rare today due to the high purity of commercial insulins. These reactions can be local or systemic and, if they are mild, they should not lead to discontinuation of treatment, since they usually decrease with continued use of the same insulin.

In severe systemic cases, hourly desensitization should be done with the hospitalized patient through the intradermal injection of very dilute doses of insulin so that the body can tolerate it.

Insulin resistance

It is characterized by a decreased response to insulin, requiring frequent dose increases to achieve the desired goal.

There is a direct relationship between this complication and obesity, for which it is recommended to reduce body weight and use highly purified or biosynthetic human insulins. If there is no improvement, intravenous steroids can be used.

Insulin edema

It is a transient condition and rarely requires treatment, but weight gain with edema has been seen in patients who have had high blood glucose levels for a long time and effectively initiate insulin treatment.

Hypoglycemia

The decrease in blood glucose levels is one of the most frequent complications of insulin use and usually occurs in patients with good metabolic control when using a higher dose accidentally.

The ingestion of foods rich in sugar or the intravenous administration of solutions with dextrose is the treatment of choice.

Somogyi phenomenon

It is the rebound hyperglycemic effect that occurs when excess insulin is administered, especially at night, and hypoglycemia is generated in the early morning.

In these patients, nighttime insulin doses should be reviewed and, at times, omitted entirely.

References

1. American Diabetes Association (2015). Insulin Basics. Living with Diabetes. Recovered from diabetes.org
2. York Morris, Susan (2017). Insulin injection sites: where and how to inject. Healthline Newsletter. Recovered from healthline.com
3. Cortez Hernández, Alfredo (1999). Insulin Treatment. Mellitus diabetes. Editorial Disinlimed, chapter VII, 119-133.
4. Wikipedia (nd). Insulin (medication). Recovered from en.wikipedia.org
5. Learning About Diabetes, Inc. (2015). Learning how to mix insulin. Recovered from learningaboutdiabetes.org
6. Yoldi, Carmen (2016). Learn how to inject insulin in three steps. Type 1 Diabetes Guide. Recovered from diabetes-cidi.org