Insulin: What Diabetics Should Watch Out for

For both type 1 and type 2 diabetics, the hormone insulin is of central importance. Insulin is often used to treat type 2 diabetes, and in type 1 diabetes it is even indispensable to enable sufferers to live as symptom-free a life as possible. In the following, you will learn which types of insulin are used for treatment, what to consider when injecting insulin, and what forms of insulin therapy are available.

What is insulin?

Insulin is a hormone produced by the body that controls the absorption of glucose (a form of sugar) into cells. It is made of protein, so it is a protein, and is produced in the pancreas. Of all the cells in the pancreas, only two percent are involved in the production of hormones. These cells consist of small associations that are distributed like islands in the middle of the pancreatic tissue. This is why they are also called Langerhans islets or islet cells after their discoverer. Insulin is produced in the body whenever the concentration of glucose in the blood increases. However, insulin is not produced and secreted continuously, but rather in waves. Insulin lowers blood sugar by absorbing sugar from the blood into the cells where it is processed. As a drug, insulin is used to treat type 1 and type 2 diabetes in order to compensate for the lack of insulin or the insulin resistance of the cells that is typical of this disease. In treatment, a distinction is made between two types of insulin: human insulin and insulin analogues.

Human insulin

After animal insulin was initially used to treat diabetes, human insulins have been produced from genetically modified yeast cells since the 1980s and are used in most cases to treat the disease. Human insulin, also known as normal insulin or altinsulin, exactly matches the insulin produced by the body in terms of chemical structure. It is therefore better tolerated than animal insulin. This is now only used to treat patients who are intolerant to human insulin. In contrast to the body’s own insulin, however, human insulin does not take effect until about half an hour to two and a half hours after injection. The effect lasts for about four to six hours. A well-known human insulin is the so-called NHP insulin (Neutral Protamine Hagedorn). This has been enriched with protamine (a certain protein). This means that the insulin is absorbed more slowly by the body. The effect of the insulin lasts for twelve to 36 hours. In addition to NHP insulin, there is also human insulin that has been enriched with zinc or surfactant (a pharmaceutical excipient). Here, too, a delay effect occurs. These insulins are therefore also called delay insulins or basal insulins.

Insulin analogues

In addition to human insulin, so-called insulin analogues are also used. Similar to human insulin, they are also produced synthetically, but their chemical structure is artificially altered to make the speed of their action much more adaptable to the needs of the diabetic. These insulins can be rapid-acting or long-acting:

  • Long-acting insulin analogues are called long-acting insulins. Their effect lasts for about a day after injection.
  • With short-acting insulin analogues, the effect already occurs after ten to 20 minutes after injection, but lasts for this only about three to five hours.

How is insulin administered?

Both types of insulin are administered as a solution by injection. For this purpose, either syringes (usually in the form of insulin pens) or insulin pumps are used. In addition, there are so-called needle-free injections (“jet-injection”), in which the insulin is injected into the skin using high pressure rather than a needle. Insulin tablets are not yet available. This is mainly due to two obstacles: As a protein, insulin would be digested by stomach acid. However, even if this problem were overcome, insulin would not be absorbed into the blood through the intestines in sufficient quantities.

What are the different forms of treatment with insulin?

There are three basic forms of insulin-only therapy:

  • Basal-assisted oral therapy (BOTI).
  • The conventional therapy (CT)
  • the intensified conventional insulin therapy (ICT)

Basal-assisted oral therapy

When antidiabetic tablets alone no longer adequately lower blood glucose levels, a combination with insulin is often useful. Basal-assisted oral therapy involves injecting long-acting insulin in addition to blood glucose-lowering tablets. This form of therapy is less likely to cause weight gain or hypoglycemia compared with insulin treatment alone.

Conventional insulin therapy (CT).

In conventional insulin therapy, affected individuals usually inject themselves twice daily with a mixture of short-acting and long-acting insulin (normal and long-acting insulin), known as mixed insulin. This therapy is mainly used for type 2 diabetics. There is a fixed meal schedule with consistent injection times, which also precisely determine the amount of food and the amount of physical activity. Although CT is easy to use for the person concerned, it leads to a strict regulation of the daily routine. In addition, the risk of hypoglycemia is highest with CT.

Intensified conventional therapy (basic bolus therapy).

Intensified conventional therapy (also called ICT or basic bolus therapy) involves injecting a long-acting insulin (basal insulin) once or twice a day and bolus insulin at mealtimes. This is fast-acting and is used to compensate for blood glucose peaks (for example, after meals). The dose and timing can be adjusted independently, depending on meals and/or physical activity. Although ICT is more time-consuming than CT or BOT due to multiple daily injections and blood glucose checks, this therapy best mimics the body’s own insulin release in healthy people. The metabolic state can thus be optimally adjusted and the risk of secondary diseases reduced as much as possible.

Insulin pen or pump?

Various methods are available to diabetics for the independent administration of insulin, which can be selected according to personal preferences or disease-related specifications. The following dosing devices are used:

  • Insulin pump
  • Insulin pen
  • Needle-free injection

Insulin pump

Insulin pumps are used primarily for the treatment of type 1 diabetes. In exceptional cases, they are also used in advanced type 2 diabetics. Insulin pumps allow flexible adjustment of the insulin dose over the course of the day through different programs, for example, during increased physical activity. The insulin is integrated into the pump via an ampoule. This indicates when the ampoule needs to be changed. The insulin is introduced into the subcutaneous fatty tissue via a plastic catheter using a cannula. The catheter is attached to the skin with a plaster. The insulin pump itself can be attached with a clip to pants or a belt, for example.

Insulin pen

Today, the vast majority of diabetics with type 2 diabetes no longer use “classic” syringes to inject insulin, but insulin pens. On the insulin pens, which are about the size of a pen, the required number of insulin units can be dosed by means of a wheel. For more information on the different models and how to use the insulin pen, see this article.

Needle-free injection (jet-injection).

In a needle-free injection, insulin is injected into the skin by applying high pressure. This pressure is generated by a spring or compressed gases. Because of its higher purchase price and the inability to adjust the depth of injection to the thickness of the fat layer, needle-free injection has not yet been able to compete with the insulin pen.

Injection: what do you need to consider when injecting insulin?

Injecting insulin usually succeeds without problems with a few simple tips and a little practice:

  • Injection areas: Legs, abdomen and buttocks are the most suitable as injection areas. On the abdomen, it is recommended to inject one centimeter above the pubic symphysis, below the lowest rib, or one centimeter from the belly button. On the legs, the preferred site is the upper third on the outside of the thighs. On the buttocks, the rear lateral area of both halves of the buttocks is best.
  • Active ingredient: depending on the active ingredient (for example, long-acting or rapid-acting, insulin analogs or human insulin), a different timing and injection range is recommended. The appropriate application should be discussed with the attending physician.
  • Injection site: the injection site should be free of inflammation, infection or abnormalities such as moles or scars. Disinfection of the appropriate site is not usually necessary outside of hospitals or nursing homes. The injection site should be changed with each new injection.

In addition, care must be taken to ensure that the insulin has been prepared according to the type of active ingredient (for example, shaking for mixed insulin) and that the pen is functional.

How should insulin be stored?

Insulin as a solution should be stored at two to eight degrees. When traveling, special cooler bags or even thermos bottles can be used. Storing insulin in a cooler is only a limited option, as the cold packs could cause the insulin to freeze due to their low temperature. However, frozen insulin loses its effectiveness.

Does insulin have side effects?

When insulin treatment is dosed correctly, there are usually no severe side effects. Obesity can be a consequence of treatment, and vision problems rarely occur at the beginning of therapy. However, if too much insulin is injected or if a muscle is hit during the injection, hypoglycemia may occur. Hyperglycemia is also possible if too much insulin is injected. In the case of type 2 diabetes, it should therefore always be weighed up whether insulin therapy is absolutely necessary or whether, for example, a change in diet combined with exercise can already bring about a sufficient improvement in blood values. In principle, a doctor should always be consulted if side effects are suspected, so that the cause of the symptoms can be clarified. Hypo- or hyperglycemia in particular can have serious consequences for the person affected.