Carbohydrate metabolism or sugar metabolism is a vital process in the human body. To ensure the functioning of the organism, an adequate supply of energy is essential. Carbohydrates are the most important source of energy for this purpose. Certain enzymes break down ingested carbohydrates into simple sugars, for example glucose, and in this form they can be used by the body. If the metabolic process runs incorrectly, a metabolic disorder is present. The most common disorder in sugar metabolism is diabetes mellitus.
What is carbohydrate metabolism?
Carbohydrate metabolism or sugar metabolism is a vital process in the human body. Figure shows glucose molecules in the bloodstream. Carbohydrate metabolism controls the absorption, conversion, transport, and breakdown of carbohydrates in the human body. The process occurs in several steps and is a vital process. Carbohydrates, also called sugars, are the most important source of energy for the human body. The individual processes that take place in carbohydrate metabolism enable the organism to make sugar molecules ingested with food usable for the body in the form of energy. Carbohydrates are broken down in the metabolism, absorbed through the wall of the small intestine and enter the body’s cells via the bloodstream. Sugar molecules that are not needed for acute energy gain are converted into fat molecules or are stored in the liver and muscles. End products of carbohydrate metabolism are excreted in feces and urine.
Function and task
Along with proteins and fats, carbohydrates are among the main groups of nutrients that are absorbed through the diet. Carbohydrates are divided into monosaccharides (single sugars), disaccharides (double sugars) and polysaccharides (multiple sugars). Important representatives of the monosaccharides are fructose, glucose and galactase. Carbohydrates that are ingested via food are usually present as di- or polysaccharides. In order for the organism to use these nutrients, the sugar molecules must first be converted into glucose. During digestion, the human body releases certain enzymes that break down ingested carbohydrates. The glucose is broken down in several metabolic steps to form adenosine triphosphate, ATP, and in this form is available to the body as an energy source. The more complex the structure of the carbohydrate, the longer the conversion process takes in the organism. The brain in particular needs glucose as a supplier of energy. After the carbohydrate has been broken down into glucose, the sugar is delivered to the respective body cells in the form of ATP via the bloodstream. If the cells are already sufficiently supplied with energy, the glucose is reassembled into new starch molecules in the body and stored in the form of glycogen in the muscles and liver. In states of hunger or during increased physical exertion, glycogen can be broken down again into glucose and provides the organism with energy. Glycogen is the carbohydrate store in the human body. However, these storage depots are limited. When the stores are already sufficiently full, unused carbohydrates are converted to fat in the liver. This fat is stored in the adipose tissue. If the energy intake exceeds the required energy over a longer period of time, this can lead to obesity.
Diseases and ailments
If the metabolism does not run smoothly, there is a so-called metabolic disorder. The body cannot utilize the nutrients it takes in, and they do not arrive where they are needed. A specific enzyme is responsible for each step of the metabolism. In the case of a metabolic disorder, therefore, there is an enzyme defect. The consequence is that substances accumulate where they do not belong and that at the same time there is a lack of certain nutrients in another place in the body. The most common disorder of carbohydrate metabolism is the so-called diabetes mellitus. This disease can be divided into two main groups. In a type 1 diabetic, the cells in the pancreas responsible for the production of insulin are destroyed. In type 2 diabetes mellitus, there is no absolute lack of insulin. Rather, the effect of insulin is reduced by the formation of resistance.Insulin is the only hormone in the body that can lower blood sugar levels. This hormone and its counterpart glucagon ensure that blood sugar levels are kept constant and are essential for life. After the intake of carbohydrates such as potatoes, pasta and bread, for example, the sugar level in the blood rises. A high blood sugar level signals that the cells are sufficiently supplied with energy. In this case, insulin is secreted, which promotes the uptake of glucose into muscle and fatty tissue, thereby lowering the blood glucose level again. Furthermore, insulin inhibits the breakdown of glycogen into usable energy in the liver. Glucagon, on the other hand, increases blood glucose levels by promoting the breakdown of glycogen into usable energy in the liver. The two hormones thus control the absorption and breakdown of carbohydrates in the human body. Without insulin, blood glucose levels in the human body remain permanently elevated. The body cannot transport the energy from carbohydrates into the cells without insulin. Furthermore, this condition damages the blood vessels and promotes various secondary diseases. These include, for example, circulatory disorders in the arms and legs, heart attacks, strokes and kidney disorders. In diabetes mellitus, it is therefore necessary to provide the body with insulin artificially. In the case of type 1 diabetes mellitus, lifelong insulin therapy is unavoidable. Type 2 diabetes mellitus does not have to be treated with medication in every case and can even be cured by a change in diet and sufficient exercise.
