insulin

What is insulin?

The body’s own insulin is a hypoglycemic hormone that is produced in the pancreas. It plays a central role in diabetes mellitus: The abnormally high blood sugar levels of patients is based either on the fact that in the body too little insulin is produced or that the sufficiently produced insulin can not develop its effect properly.

In the first case, one results absolute insulin deficiency, It is typical of type 1 diabetes: This form of diabetes can only be treated with insulin preparations. This means that the missing hormone must be regularly supplied from the outside (insulin therapy). There are various insulin preparations available.

Rarely, insulin therapy is also needed for type 2 diabetes. The patients usually have one relative insulin deficiency which is based on insufficient insulin action. This can usually be treated with a diet change, sports and possibly hypoglycemic tablets (oral antidiabetics). Only if this is not enough to lower the elevated blood sugar, type 2 diabetics get insulin.

How is insulin administered?

Insulin-dependent diabetics can now conveniently inject insulin with wafer-thin needles and an insulin pen that looks like a filler. Rarely does an automatically working insulin pump replace the manually administered syringes.

There are various insulin preparations and different treatment regimens on how to administer the injections (Conventional Insulin Therapy, Intensified Insulin Therapy). Which therapy and which preparation is suitable for a particular patient depend, inter alia, on their willingness to deal with the diabetes illness and the treatment methods.

Insulins: effect

The insulins administered in diabetes therapy must mimic the necessary hormonal action in the patient’s body. This is the only way to reduce high blood sugar levels and avoid secondary diseases (such as diabetic foot or diabetic retinopathy).

Basal-bolus principle

The healthy pancreas distributes evenly throughout the day low insulin levels. They should cover the basic need for insulin and thus maintain vital metabolic processes (basal rate).

In addition, the pancreas releases extra insulin at each meal to utilize the sugar from the diet (bolus). The amount of insulin secreted by the pancreas depends on dietary habits, physical activity, time of day, and other conditions (such as acute illnesses).

How much a diabetic has to inject insulin to cover basal rate and bolus is individually different.

Insulins: application

Depending on their origin, the insulins used for diabetes therapy can be divided into animal (such as porcine insulin) and artificial insulin (human insulin, insulin analogues):

Previously, diabetics were treated with insulin isolated from the pancreas of pigs and cattle (Porcine insulin, Bovine insulin). The human immune system reacts to the foreign substance but often with the formation of antibodies. This affects the effect of insulin. This is why pork and bovine insulin are used much less frequently in this country than in the past.

In the mid-1980s, it was possible for the first time to genetically produce insulin in large quantities. This human insulin is identical to human insulin. It is the most commonly used insulin in diabetes therapy. Animal insulins and human insulins (without the addition of effect-prolonging substances) are also known as Normal insulins because they have the same structure as human insulin.

Since the 1990s, so-called insulin analogues used for the treatment of diabetics. They are produced like human insulin artificially (genetically), but differ slightly in their structure. Depending on how their structure was altered, they either work faster and shorter than normal insulins or slower and longer than NPH retardation insulins (normal insulin with NPH addition for a delayed effect).

Classification according to entry and duration of action

The different insulins are also classified according to their duration of action and the profile of action. It depends on these two characteristics how and when an insulin preparation is used. The following is an overview and then a more detailed description of the various insulins and their application.

(Note: the onset of insulin depends on several factors, including the location of the injection.)

Short-acting insulins

Insulin analogues:

• Effect: about 5 to 10 minutes after administration
• Efficacy maximum: about 1 to 1.5 hours after administration

• Duration of action: approx. 2 to 3 hours

Normal insulins (Human insulin, porcine insulin, bovine insulin)

• Effect: about 15 to 30 minutes after administration
• Efficacy maximum: about 1.5 to 3 hours after administration

• Duration of action: approx. 4 to 8 h

Intermediate insulins

(Insulin analogs, human insulin or porcine insulin delayed with NPH or zinc)

• Onset: about 2 hours after administration
• Maximum effect: about 4 to 6 hours after administration

• Duration of action: approx. 12 to 14 h

Long-acting insulins

(Insulin analogs, human insulin, porcine insulin)

• Enter: slow
• Effective maximum: depending on the delay principle

• Duration of action: depending on the delay principle; usually up to 24 h

mixing insulins

(Insulin analogs, human insulin, porcine insulin)

Solid mixture of different insulins (see below).

Fast and short-acting insulins

They cover the insulin requirements at meals (bolus). Therefore, medics also speak of bolus, eating, meal or correction insulin.

• normal insulin (formerly: old insulin)

The effect begins after about 15 to 30 minutes. Therefore, the insulin must be injected half an hour before eating (spray-eating distance). After 1.5 to 3 hours, the effect reaches its peak. The total duration of action is about 4 to 8 hours.

• insulin analogues

The effect can occur here after about 5 to 10 minutes. In contrast to regular insulin, there is no need to maintain a time interval between injections and eating. The maximum effect is reached after 1 to 1.5 hours. Overall, these insulin analogs are shorter than regular insulin: their duration of action is about 2 to 3 hours.

Slow and long-acting insulins

They cover the food-independent basic requirement of insulin (basis) and are therefore also called basal insulins.

• Intermediary insulins

The addition of various substances (protamine, zinc, surfing) can delay the onset and duration of human insulin. Of importance are still mainly delay insulins with protamine addition, so-called NPH insulins (NPH = neutral protamine hawthorn). Its effect begins about two hours after spraying and reaches its maximum after about four to six hours. Then the effect flattens off again. The total duration of action of NPH insulins is about 12 to 14 hours.

NPH insulin can be stably mixed with normal insulin in any ratio. There are therefore numerous insulin preparations with constant NPH / normal insulin mixtures on the market. Frequently, however, both components are also mixed together just prior to injection in the syringe.

The effect of the intermediary insulins is not uniform. This can lead to nocturnal hypoglycaemia, when the insulin reaches its maximum effect. In the morning, however, when the effect wears off, increased levels of sugar are possible.

• Long-acting insulin analogues

The duration of action of the long-acting insulin analogues is usually up to 24 hours. Therefore, they only need to be injected once a day. In contrast to the intermediary insulins, these insulin analogs are relatively uniform over the entire period and have no maximum effect. Therefore, the risk of nocturnal hypoglycaemia is lower, and in the morning, the sugar levels remain lowered.

Insulin analogs are easier to use than delayed humanisulins. They are present as a clear, dissolved liquid, are therefore easy to dose and adjust the blood sugar very evenly. In contrast, human insulins deposit as crystals in the ampoule (suspension). Therefore, they must be mixed thoroughly before each injection to avoid dose fluctuations.

mixing insulins

Mixed insulins are ready-made mixtures of a short-acting and an intermediate or long-acting insulin. They are available in different proportions. For some people with diabetes mellitus, such solid mixtures are more convenient. But this also binds the diabetic into a more rigid concept than individual combinations.

Inhaled human insulin

The first inhaled insulin was approved in Germany in 2006. However, the manufacturer withdrew the product a year later because the inhaler is very large and the treatment is much more expensive than with insulin syringes. So far, no new ones insulins brought to the German market for inhalation.