Currently, there are two main types of diabetes mellitus, differing in the cause and mechanism of occurrence, as well as in the principles of treatment.
Type 1 diabetes mellitus
Type 1 diabetes mellitus (insulin-dependent diabetes) results from the direct destruction of the cells in the pancreas that produce the hormone insulin. Due to a decrease in the number of beta cells of the islets of Langerhans, a decrease in the concentration of insulin in the blood occurs. Insufficiency of insulin leads to a disruption in the flow of glucose from the blood into the cells of the human body. A strange situation arises – in the blood of a patient with type 1 diabetes mellitus there is a lot of glucose, and the cells are “starving”. The destruction of cells occurs due to the aggression of the patient’s own immune system against the islets of Langerhans, or due to exposure to viral factors, intoxication with harmful substances, damage to the pancreatic tissue during the development of tumors in it or in trauma, removal of pancreatic tissue during surgery. In the immune form of diabetes mellitus, heredity is important – in the presence of diabetes in one of the parents, the likelihood of its occurrence in children is significantly increased compared to the average risk in the population. The destruction of cells is irreversible, so type 1 diabetes cannot be cured. The only way to remedy the situation is to administer insulin, which is still possible only by parenteral (injection) route. Insulin preparations for oral administration have not yet been developed.
Type 1 diabetes usually occurs during childhood or adolescence. The onset of the disease is usually violent, with the development of ketoacidosis and a significant increase in blood glucose levels. It is not uncommon for patients to find out about their illness when they are admitted to an intensive care clinic. Treatment begins immediately with the introduction of insulin. There are no other methods of treating type 1 diabetes mellitus; delay in the appointment of therapy can lead the patient to rapid death due to diabetic coma.
In the treatment of type 1 diabetes mellitus, the insulin preparations used and the scheme of their administration are important. The quality of diabetes compensation is improved with the use of automated insulin pumps that dose insulin according to a pre-assigned program.
Type 2 diabetes mellitus
Type 2 diabetes mellitus is accompanied by normal or increased insulin production. The reason for the development of the disease is the untimely flow of insulin into the blood, as well as a decrease in the sensitivity of the patient’s body cells to insulin. In type 2 diabetes mellitus, insulin in the blood is usually sufficient (or its level is even increased), but the cells “do not feel” it, and glucose cannot get from the blood into the cells. An impaired insulin sensitivity is termed “insulin resistance”.
In type 2 diabetes mellitus, insulin deficiency is not quantitative (lack of insulin production), but qualitative (insufficient insulin effect). Even in the presence of sufficient or high concentrations of insulin in the blood, it does not work well enough. There are various reasons for the poor effectiveness of insulin.
In some patients, the sensitivity of receptors on the cell surface to insulin is lost. The cells of the body lose their ability to bind insulin to their surface receptors because these receptors are damaged. Insulin cannot activate receptors on the surface of cells, and those, in turn, cannot activate the mechanism of glucose absorption into the cell. This form of type 2 diabetes is often referred to as “fat diabetes” because it is more common in overweight patients.
It also happens that insulin is produced defective, not suitable for normally formed receptors. In this case, the receptors on the cell surface are completely normal, but insulin cannot bind to them, because it has the wrong structure. This form of type 2 diabetes is called “thin diabetes”.
One of the main reasons for the development of type 2 diabetes mellitus is heredity – usually, one of the blood relatives of a patient with diabetes is diagnosed with the same disease. Obesity also plays an important role in the development of type 2 diabetes. Type 2 diabetes mellitus is much more common than type 1 diabetes – it is detected in 2-10% of the population. Type 2 diabetes is treated not with insulin, but with drugs that increase the sensitivity of cells to insulin. The use of insulin in the treatment of type 2 diabetes is also possible, but it is used relatively rarely, only in cases of resistance to hypoglycemic drugs.
Type 2 diabetes is less severe than type 1 diabetes. The symptoms of type 2 diabetes mellitus are less pronounced, so the patient often does not notice them immediately, which leads to a delay in the diagnosis of diabetes and a late start of treatment. Meanwhile, timely diagnosis of type 2 diabetes mellitus is very important, since only in the early stages is it possible to effectively prevent the development of complications. The insidiousness of diabetes lies in the fact that it is in the early stages, when treatment can be very effective, that patients most often do not feel their disease and are not concerned about its treatment, therefore it is quite difficult to persuade them to make a drastic change in their lifestyle and take the necessary medications. At the stage of development of complications, when the quality of life begins to deteriorate significantly, patients with type 2 diabetes are already ready to undergo treatment, but this treatment is already less effective.
For both types of diabetes, a healthy diet is a critical part of treatment.
In addition to diabetes mellitus types 1 and 2, there are several more less common types of this disease.
The cause of the development of MODY diabetes is a genetic defect that disrupts the secretion of insulin by the beta cells of the islets of Langerhans in the pancreas. MODY-diabetes is not very common – about 5% of patients with diabetes mellitus have this form of the disease. The onset of the disease usually occurs at a fairly early age. Treatment of this type of diabetes mellitus occurs with the use of insulin, however, to achieve optimal blood glucose levels, the patient requires low doses of insulin. This type of diabetes can be easily compensated for. Figuratively speaking, MODY-diabetes occupies a “middle” position between type 1 and type 2 diabetes mellitus.
Gestational diabetes mellitus
Gestational diabetes occurs during pregnancy. After childbirth, this type of diabetes mellitus may disappear or be less severe. There is a gestational type of diabetes mellitus in 2-5% of pregnant women. Women who have gestational diabetes during pregnancy often develop type 2 diabetes. Children born to mothers with gestational diabetes are overweight and may have congenital malformations (diabetic fetopathy).