Glucagon is a hormone of the pancreas and an important regulator of blood glucose levels in the body. It is mainly used as an agent in hypoglycemic states during diabetes.
What is glucagon?
Glucagon is mainly used as an agent in hypoglycemic states during diabetes. Glucagon is the direct antagonist of insulin. While insulin lowers blood glucose levels, glucagon exerts just the opposite effect. Chemically, glucagon is a polypeptide consisting of 29 amino acids and is produced in the islets of Langerhans in the pancreas. As a rule, the secretion of glucagon is not subject to as great fluctuations as insulin. Both hormones regulate the energy metabolism of the organism and ensure a relatively constant blood glucose level. If, for example, there is a need for energy in stressful situations, the production of glucagon is stimulated in order to provide energy quickly in the form of glucose.
Pharmacologic action
The interaction of the two hormones is controlled by a complicated regulatory mechanism. Changes in blood glucose levels due to diet determine which hormone is produced with priority. Carbohydrate-rich foods immediately raise blood glucose levels, leading to an increase in insulin production. However, if a lot of energy is consumed through physical activity or stress, glucose must be replenished to provide energy. This in turn stimulates glucagon production. A low-carbohydrate and high-protein diet also leads to increased secretion of glucagon. Furthermore, hypoglycemia also immediately stimulates glucagon production. Insulin is responsible for storing excess energy in the form of fat in the fat cells or glycogen in the liver. When energy is needed, however, the organism must provide rapidly available energy. Glucagon does this in two different ways. First, it stimulates glycogenolysis of glycogen. Glycogen, which is stored in the liver as a complex carbohydrate, is broken down again into glucose. Glycogen, like starch, is a multisugar composed of glucose units. During glycogenolysis, this molecule is broken down again into its individual components, i.e. into individual glucose molecules. However, glucagon can also convert starting materials that are primarily not sugars into glucose. This process is called gluconeogenesis. Proteins and fats serve as the starting materials here. For example, amino acids are converted into sugar when there is an increased demand for glucose. During fat degradation, fatty acids and glycerol are formed first. Glycerol is then the starting material that can be converted into glucose. As a side effect of the increased protein and fat breakdown, increased urea and fatty acid concentrations in the blood result. At the same time, glucagon inhibits protein, fat, and glucogen synthesis.
Medical application and use
The mode of action of glucagon also determines its applications. For example, it is often used as a medication in diabetics. Conditions of hypoglycemia often occur, especially in diabetics. This can happen if too few carbohydrates are supplied during insulin doses. These hypoglycemic (low blood sugar) states can become life-threatening, as the body is no longer supplied with sufficient energy. In particular, an undersupply of glucose to the brain is very critical. In these cases, a solution of glucagon is injected under the skin or intramuscularly. The blood glucose level then normalizes within a short time. There is also a glucagon test that can determine the concentration of C-peptide. The C-peptide is a precursor of insulin. This rarely used test is a functional test for the pancreas and can be used to distinguish between diabetes A and diabetes B. In addition, glucagon is used as a drug to immobilize the stomach and intestines for endoscopy of the intestines or x-ray of the stomach. Another use is for poisoning with beta-blockers.
Risks and side effects
Side effects occur very rarely during treatment with glucagon. In isolated cases, nausea and vomiting may occur if the injection is administered too quickly or at elevated concentrations. However, overdose has no long-term negative effects. Interactions with other drugs are also generally not known. Even when glucagon is used in diabetic pregnant women, no side effects occur because it cannot cross the placental barrier.However, glucagon should not be used in certain rare tumors of the pancreas, such as glucagonoma or insulinoma and pheochromocytoma, a tumor of the adrenal medulla.
