What are the reasons for diabetes

Causes of Type 2 Diabetes

Several causes or triggers play a role in the development of type 2 diabetes. These include:

  • hereditary factors
  • Obesity and lack of exercise
  • decreased sensitivity to insulin (insulin resistance)
  • an impaired release of insulin
  • as well as impaired production of certain intestinal hormones.

In order to understand the development of type 2 diabetes, it is helpful to take a closer look at the sugar metabolism.


Blood sugar in healthy people

Carbohydrates are broken down by digestion to such an extent that they are absorbed in the form of sugar or glucose by the mucous membrane cells in the small intestine and released into the blood. The blood first transports the glucose to the liver and then to the individual cells of the organs and tissues. If glucose gets into the blood, the blood sugar level rises and the pancreas releases more insulin. Insulin ensures that the glucose is channeled into the cells as an energy donor and that this lowers the blood sugar level again. All cells have many insulin receptors on their surface. Insulin is the "key" that unlocks the cells for glucose. Glucagon, the antagonist of insulin, is increasingly released by the pancreas when there is little sugar in the blood (low blood sugar level). Glucagon causes more glucose to be formed in the liver (gluconeogenesis) and released into the blood, thereby preventing hypoglycaemia. Due to the interaction of the two opposing hormones, the body is normally able to supply the body with glucose without great fluctuations. H. with energy to ensure.

Fig. 1. Overview of sugar metabolism


Blood sugar in diabetes

Type 2 diabetes develops slowly and usually over many years. In the early stages of the disease, the cells of the pancreas still produce enough insulin. Over time, however, the cells of the muscles, liver and adipose tissue become less sensitive to insulin (insulin resistance). This means that the hormone is less and less able to smuggle sugar from the blood into the cells. As an “answer”, the pancreas tries to compensate for this disorder by increasing insulin production. The amount of insulin in the blood of those affected can therefore be normal, sometimes even increased, during this phase of the disease. First of all, there is an excessive and prolonged rise in blood sugar after the intake of carbohydrates (impaired glucose tolerance). At this stage, type 2 diabetes can often still be managed well with exercise, weight loss and, if necessary, additional tablets. After many years of constant excess production of insulin, the function of the insulin-producing cells increasingly declines and insulin production finally comes to a complete standstill. Then the person concerned has to get the insulin from the outside, i. H. Inject insulin. The relative insulin deficiency at the beginning of type 2 diabetes (insulin resistance) turns into an absolute insulin deficiency. A lack of insulin means that less and less glucose is getting from the blood into the body's cells, so that the blood sugar levels rise and ultimately diabetes is achieved.

Fig. 2. Overview of type 2 diabetes: insulin insensitivity and increased blood sugar level


Deficiency of intestinal hormones as a cause of a disturbed sugar balance

In type 2 diabetes, there is also the fact that certain endogenous intestinal hormones, such as GLP-1 (glucagon-like peptide-1), are not produced in sufficient quantities. GLP-1 is produced in the intestine and released into the blood when you eat. However, it is broken down relatively quickly in the body by an enzyme called DPP-4 (dipeptidyl peptidase-4). The GLP-1 hormone has a regulating effect on the sugar metabolism by stimulating the production of insulin in the pancreas, inhibiting the production of glucagon, delaying the emptying of the stomach and stimulating the feeling of satiety. A deficiency in GLP-1 is therefore the cause of impaired sugar utilization in the body.


The function of the kidney

The kidney fulfills three key functions in glucose metabolism: it produces glucose itself, but also uses glucose for its own metabolism and is responsible for recovering (reabsorption) large amounts of glucose from the urine.

The latter is the crucial point: in healthy people, this recovery is an important mechanism. Because it prevents the blood sugar from being excreted with the urine and thus being lost to the body as a valuable source of energy for maintaining the body's functions.

However, people with type 2 diabetes are known to have an excess of sugar in their blood. In addition, paradoxically, in type 2 diabetics, the reabsorption of blood sugar is increased. The reason for this is that a transport protein called SGLT-2 (sodium-glucose-contransporter-2), which is responsible for recovering sugar from the urine, occurs more frequently in type 2 diabetics. In this way, the kidneys in type 2 diabetics help maintain the elevated blood sugar level.