In short, diabetes mellitus is a disease in which the body does not produce enough insulin or its action is impaired. But what is insulin? Insulin is a hormone. What is a hormone?
A hormone is a substance that is produced in the body and the hormone is different from other substances produced in the body that the hormone affects the whole organism, for example, growth, sex determination, etc. Insulin, like a hormone, is responsible in the body for storing and consuming energy sources, which are proteins, fats and carbohydrates for the body.
So, insulin helps to turn the food you eat into energy and energy stores that the body needs for normal functioning. As a result, when insulin is not enough, then the body does not have enough energy for life.
Sounds simple enough. Is not it? Well, it should also be noted that different people may have their own problems with the use of insulin as a drug. Someone does not use it at all, and others - in small doses or not effective enough. In order to somehow streamline the recommendations for the management of diabetes and, in particular, insulin treatment, it is divided, first of all, into two types - the first and the second. Some women develop diabetes for the first-time during pregnancy and therefore it is distinguished as a special type - pregnant diabetes. Doctors sometimes call itgestational diabetes mellitus, from the English word gestation, "gestation", which translated into Russian is pregnancy. Most cases of diabetes can be attributed to one of these three groups, which is further elaborated in other chapters.
Other types of diabetes mellitus are caused by hereditary (genetic) diseases, drugs, or certain diseases. As a result, not all people with diabetes can be attributed to the first or second type. In fact, there are more than 10 different forms of diabetes! But all these are quite rare diseases and usually their treatment ultimately coincides with that presented for 1 or 2 types of diabetes.
In diabetes, the metabolism is impaired due to insufficient formation of insulin of its own (type 1 diabetes or type 1 diabetes), or a violation of its effect on tissue (type 2 diabetes or type 2 diabetes). Insulin is produced in the pancreas, which is located directly behind the stomach, between the spleen and the loop of the duodenum. It weighs 70-100 g and, besides insulin, produces daily pancreatic juice, which enters the duodenum and plays an important role in the digestion of fats, carbohydrates and proteins.
Insulin is produced in the so-called beta cells, located throughout the gland in small groups called "Langerhans islets". An adult healthy person has about 1 million of these islets, the total total weight of which is 1-2 g. Along with beta cells, the so-called alpha cells that produce the hormone glucagon, which acts in the body oppositely, are located in the pancreatic islets. insulin.
Insulin is a protein molecule consisting of two amino acid chains, and it plays a central role in human metabolism. The biological effect of insulin consists primarily in accelerating the uptake of sugar by cells. Note that the sugar in the body is represented only by the glucose molecule.Glucose is used for energy, without which organs and tissues cannot perform their tasks (for example, muscles will not contract and the brain will think). Along with this, insulin promotes the entry of amino acids into cells, which are the building blocks for protein molecules, i.e. insulin causes and the accumulation of protein in the body. Insulin also saves and accumulates fat in the body.
If you imagine the cell of the body as a small house with an entrance door and a lock, then insulin can be viewed as a key to the lock that opens the entrance door for glucose.
Who is sick with diabetes?
You may have the feeling that you are suffering from a very rare disease. No - you are not alone! According to official data, currently 2,834 million people with diabetes have been registered in Russia, which is about 3% of the population. From here it is quite likely that you know someone who has been ill with diabetes for a long time. This could be someone from schoolmates, or members of a group that you attend, or employees. Diabetes occurs in both children and adults, and those who are in good or in bad physical shape and a person of any race or ethnic group.
But no one who has diabetes has a bright and large identification mark "And I have diabetes too!"? Different people have diabetes with various symptoms, and this determines the difference in its treatment. It may well be that the prescribed treatment for your friend does not at all coincide with yours and at the same time both methods of treating diabetes will be correct.
Undetected, latent diabetes
It was mentioned above that in Russia, according to official data, about 3-5% of the population suffers from diabetes. However, the results of control and epidemiological studies and clinical examination of a part of the working-age population within the framework of the National Health Project show that the prevalence of hidden diabetes mellitus reaches 7% and the actual number of people with diabetes in Russia can be about 8 million. So, more than half of those with diabetes do not know that they are ill and, possibly, quite a long time ago. This is due to the fact that when diabetes mellitus occurs after 40 years, in the first years of the disease it does not manifest any symptoms or they are so insignificant that a person does not pay attention to them. This is typical of the so-called second type of diabetes, the prevalence of which is 10 times higher than the first type. In the first type of diabetes, severe symptoms of diabetes develop very quickly, within days of the onset of diabetes, and, the younger the person, the symptoms appear faster and more brightly. Especially in children who, within a few hours after the first signs of the disease appear, may faint and die (diabetic coma) if insulin treatment is not prescribed in a timely manner. Therefore, among those who have type 1 diabetes mellitus, its typical symptoms (thirst, weight loss, etc.) are always observed.
Diabetes - a global epidemic
You may have heard that more and more people get sick with diabetes. Unfortunately, this is absolutely true. According to experts of the International Diabetic Federation, published in the diabetic atlas of 2009, there are currently 285 million people with diabetes in the world, representing 6.6% of the world's population. By 2030, an increase in the prevalence of diabetes is projected to 438 million people, and the total prevalence of this disease will be 7.7%. The increase in prevalence occurs mainly due to type 2 diabetes, which accounts for 85-95% of all cases of diabetes in developed countries, and an even larger percentage in developing countries. Mortality from diabetes will double by 2030 compared with 2005, according to estimates by the World Health Organization (WHO).
The prevalence of diabetes in Russia and other countries
According to experts of the International Diabetes Federation, Russia ranks fourth in the world in the prevalence of diabetes. Most diabetes in India, China and the United States.
A brief historical background of diabetes
Diabetes is one of the oldest diseases known to humanity, a description of the manifestation of which was found in ancient manuscripts and in early medical texts. An ancient Egyptian medical text written around 1550 BC describes a disease in which "too much urine is lost." The Roman physician Arathaus , who lived in the second century BC, gave the name "diabetes" of this disease, which in Greek means "siphon" or "leak." That is, this term reflects one of the typical symptoms of diabetes - loss of fluid with urine, excessive urination. Aratheus wrote that the body of a patient with diabetes "leaves" with urine. He also wrote: "Diabetes is a mysterious disease." This statement is true today, because the cause of diabetes remains largely unexplained and, especially, its late complications. In the 17th century, physician Thomas Willis first discovered the sweet taste of urine in diabetic patients, which was later used by doctors to diagnose this disease. On this basis, a method of diagnosing diabetes was "developed": it was proposed to urinate next to the anthill, and if the ants reach for urine, then it contains sugar. It was also added, by the way,sugar diabetes, reflecting the loss of sugar in the urine. Consequently, the expression "diabetes mellitus" means, in fact, "sugar bleeding" or "losing sugar", which reflects one of the characteristic features of the disease - loss of sugar in urine. In 1889, Paul Langergans discovered microscopic examination of the pancreas and characteristic clusters of cells, which he called "islands", but could not explain their significance for the organism. Mehring and Minkowski in 1889 caused diabetes mellitus in animals, removing the pancreas. In 1921, researchers Banting and Best managed to get insulin from pancreatic tissue, which in a dog with diabetes eliminated signs of the disease. In 1922, insulin was first successfully used to treat a patient with diabetes. In 1960, the chemical structure of human insulin was established, in 1976, human insulin was synthesized from pig insulin, and in 1979, full synthesis of human insulin was carried out by genetic engineering. At present, not only human synthetic insulin is used for the treatment of diabetes, but also synthetic human insulin analogs, which have improved medication qualities in comparison with human insulin.
Glukoza and diabetes
What is glucose?
In everyday life, the feeling of sweetness is attributed to sugar, which is contained in the product. But sugar is a complex substance consisting, in turn, of "simple sugars," including glucose, which is also very sweet. And in humans and other animals, except glucose, there are no other sugars. So, when we say blood sugar, it is like saying blood glucose. And, generally speaking, the latter definition is more accurate. Hence, modern doctors prefer to talk about blood glucose, not blood sugar. But the expression "blood sugar" is also correct, if you understand that in fact it is still "blood glucose". Similarly, not sugar, but actually glucose is excreted with urine.
So, glucose belongs to the simplest sugars and in the body, it is the most important source of energy (biofuel), like gasoline, which is the source of energy for the operation of a machine.
How does glucose work?
Glucose is needed by the body as an energy source. At the same time gets her body with food. Yes, with food! When breakfast, lunch, dinner or snack.
After a person has eaten a certain dish or product, he eventually turns into glucose in the digestive system, which comes from the stomach and intestines into the blood. Blood glucose is distributed to all cells of the body, in which it "burns", giving energy to the work of the cells. Cells are doing a variety of work aimed at maintaining the vital functions of the body. In order for the body to be constantly in the best physical shape, glucose must be constantly available to the cells of the body. To do this, the concentration of glucose in the blood must be in the so-called normal range. If there is little glucose in the blood, there is not enough energy, and if there is a lot of it, then it is stored and the body weight increases.
The optimal or "normal" blood glucose level can be checked using special tests. Normal blood glucose level on an empty stomach is in the range of 4.0-5.6 mmol / l. On an empty stomach, this means that there was no food intake for at least 8 hours.
But the question arises - how can the body so accurately maintain the level of blood glucose? Answer: due to the fine balance between the hormones that regulate energy metabolism and the reserves of energy sources in the body (carbohydrates, fats and proteins).
You will encounter the fact that medical personnel often do not speak such a long phrase as "blood glucose", but use the abbreviated term "glycemia". The word "glycemia" combines pieces of two words: (1) " Gli -" is a slightly disfigured piece of the word "glucose"; (2) "- emia " is the ending that physicians stick to everything that is related to blood, for example, anemia (anemia), which means "glycemia" is glucose in the blood.
The pancreas usually does not attract the attention of a person until he stops his work. It plays a very important role in digestion and is located behind your stomach.
The pancreas produces many different hormones, including two of them, which regulate the level of blood glucose - insulin and glucagon. These hormones are produced by special clusters of cells in the pancreas called the islets of Langerhans. In these islands, alpha cells produce glucagon, and beta cells, insulin. The hormones produced by the pancreas enter the bloodstream, from where they exert their regulating effect on the entire body.
The islets of Langerhans are named after the German physician Paul Langerhans, who first described them in 1869, when he was a medical student. He presented his observation in the form of theses, in which he described these cells as looking different from the surrounding pancreatic tissue. But what was the function of these cells Langergans did not know.
Insulin and glucagon
Insulin and glucagon are two very important hormones that maintain blood glucose levels in the normal range. Insulin helps glucose enter cells from the blood and as a result, blood glucose levels fall. Glucagon, on the other hand, contributes to an increase in blood glucose levels when it is reduced by insulin. In connection with this special action of glucagon, the drug "Glucagon" was developed, which can be administered to patients with diabetes to eliminate a sharp drop in blood glucose (hypoglycemia).
Insulin can be represented by some "key house", which opens the "door" in the outer wall of the cell to pass through it exclusively glucose. Such a kind of personal entrance for Miss Glucose with the gatekeeper Insulin. Insulin also inhibits the production of glucose by the liver when it is not necessary. For example, after taking glucose, when it enters the blood from the intestine in sufficient quantity.
Insulin production by the pancreas depends on the blood glucose level - the higher it is, the more insulin is produced. This mechanism ensures the exact correspondence of insulin production to food intake - the more glucose from the gastrointestinal tract enters the blood, the higher its concentration in the blood and, accordingly, the higher the production of insulin.
Once again, I draw your attention to the fact that insulin does not act on all tissues, but only on three, but the largest in the body - fat, muscle, and liver. And this is not by chance, since its task is to store excess glucose coming from food. And what is best suited for this? Large storage space.
In the liver, insulin puts glucose in dense packs (which are called "glycogen"). Adipose tissue is a virtually unlimited "storage room" and in it, glucose is immediately converted into fat, which is stored in fatty bags-cells called adipocytes. Finally, in muscle tissue, glucose is converted into protein and stored in this form. If glucose is not enough, for example, 4-5 hours after a meal, then it is first withdrawn in its pure form from the liver warehouse (glycogen). Removing glucose from the liver helps hormone glucagon ("glucose drives"), especially since it decreases with a decrease in blood glucose. When the reserves of "pure" glucose are exhausted, the body takes energy from the fat depots and finally, if there is not enough fat, muscle protein reserves are used.
The remaining, so-called insulin-independent tissues, absorb glucose from the blood without the help of insulin, especially the brain, which is the main consumer of blood glucose. Insulin-independent tissues are not the place of deposition of excess glucose, they only burn it without residue.It is for this reason that the liver, adipose tissue and muscles are called insulin-dependent tissues, and the rest are insulin-independent.
The above ideas about insulin, glucagon and blood glucose are essential for understanding the development of diabetes and the principles of its treatment.
Discovering the cause of diabetes
In 1776, scientists discovered that glucose is in the blood of both a diabetic patient and a healthy person. This led them to conclude that in people with diabetes, glucose is released from the blood into the urine, but they still don’t know how.
About a hundred years later, in 1889, two German physiologists Oscar Minkowski and Joseph von Mehring accidentally discovered that the pancreas has something to do with diabetes. They investigated in experiments on dogs how fat is used in the body and for this purpose the pancreas was removed. To their great surprise, animals began to urinate very often. They decided to examine the urine for glucose and found that the dogs had diabetes. From this they concluded that some substance is produced in the pancreas that prevents the development of diabetes.
Another 30 years passed, and scientists discovered this mysterious substance - insulin - in the pancreas.
Early symptoms of diabetes
As mentioned above, diabetes does not produce enough insulin (T2D) or does not produce it at all (Td1). Or the effect of insulin is violated (SD2). As a result, glucose is unable to enter the insulin-dependent tissues and begins to "hang" in the blood. In fact, the blood is converted into a "warehouse" for glucose, since the main storage areas, the liver, adipose tissue and muscles, do not accept it. But blood is a very small "warehouse" in volume, and it very quickly overflows with glucose, which is manifested by an increase in its concentration in the blood.
An increase in blood glucose has various adverse effects on the body, depending on the degree of increase. First of all, the body tries to get rid of excess glucose in the blood and begins to dump it into the urine and, accordingly, into the external environment. Hence, increased urination with a high level of blood glucose, which ultimately causes dehydration, especially if a person drinks enough liquid. And excretion of an increased amount of fluid causes great thirst. Hence the second typical symptom of diabetes - increased fluid intake.
Insulin is not only involved in the storage of energy substrates (in the form of glycogen, fat and protein), but also is the custodian of these reserves - it blocks their excessive consumption. But as soon as there is not enough insulin, the reserves start to "squander" - the glycogen reserves are completely consumed within a few hours, and this is followed by a rapid breakdown of fat and muscle tissue. And so, there is the next characteristic symptom of diabetes - fast and dramatic weight loss. Stocks of energy substrates are exhausted - the body suffers from an energy deficit. And from here the following symptoms - severe weakness, and sometimes a constant feeling of hunger ("wolf hunger").
So, the early symptoms of diabetes are:
- frequent and abundant urination;
- strong thirst;
- constant, insatiable feeling of hunger
But all these symptoms appear only when the level of glucose in the blood becomes very large, more than 10 mmol / l. In diabetes mellitus type 2 for several years, an increased level of blood glucose may not reach such high values. This is due to the fact that insulin deficiency in this form of diabetes is growing slowly and in the first years it is quite enough to maintain glucose at moderately elevated numbers not reaching 10 mmol / l. In this case, diabetes does not cause any of the above symptoms. And usually, for the time being, diabetes is not diagnosed (hidden) or is detected by chance during a follow-up examination or examination for a reason other than diabetes.
However, it should be noted that even a moderately elevated blood glucose level is very unhealthy - although it slowly but surely affects the blood vessels in diabetes, both large (atherosclerosis) and small eye vessels (blindness), kidneys (renal deficiency) and nerves (diabetic neuropathy). Hence, the timely diagnosis of diabetes mellitus, at its earliest stages, is very important.
In contrast to T2DM, the onset of T1DM is characterized by a rapid deterioration of health and more pronounced symptoms of dehydration. In this case, it is necessary to urgently prescribe insulin preparations. Otherwise, the metabolism is quickly disturbed, which can lead to a life-threatening condition - diabetic ( ketoacidotic ) coma. A key role in the development of this coma is a violation of fat metabolism. Due to lack of insulin, the body begins to use the energy stored in fat depots. A large amount of "fat" goes into the blood and part of it in the liver turns into ketone bodies, which enter the blood and have a toxic effect on the body. A ketoacidotic coma develops ("keto" - from the word "ketone", and "acidotic "- indicates that the blood becomes acidic).
It should be noted that for the diagnosis of diabetes it is absolutely not recommended to use a glucometer, which diabetics determine in their blood glucose. The blood glucose meter is a household device and the error in determining its glucose concentration in the blood is unacceptable for accurate diagnosis of diabetes. This is especially true for type 2 diabetes, when, at the onset of the disease, an increase in blood glucose may be small and not be tracked by a glucometer. Or, on the contrary, based on the results of a blood glucose test using a glucometer A diagnosis of diabetes will be made to those surveyed who do not have diabetes. So, the diagnosis of diabetes can be made only on the basis of a study of blood glucose in the laboratory, on special precision equipment, and not using a glucometer in the home or other conditions.
I draw your attention to another important fact, when diabetes is diagnosed by the level of glucose in the blood. Today there are two methods for determining blood glucose:
- in the blood, as it is, what is usually called the study of glucose in "whole blood";
- in the blood plasma.
In order to obtain blood plasma, red blood cells and other blood elements are removed from whole blood and only then in the liquid remaining from whole blood, glucose is examined. This fluid isolated from the blood is called blood plasma. And it turns out that the rate of glucose concentration in whole blood is slightly lower than in blood plasma. So, if you get an analysis in your hands that shows fasting blood glucose concentration, then you should check with your doctor or laboratory technician how glucose was tested - in whole blood or blood plasma. And this is how it should be written in the conclusion of the laboratory, and not just in the blood. It should be noted that recently they prefer to investigate glucose in the blood plasma. Therefore, in order not to be confused, in this book the norms of glucose content are given only in blood plasma, but not in whole blood.
The diagnosis of diabetes mellitus can be made by the level of blood glucose in one of three studies - on an empty stomach, by a random blood glucose test within a day or in a glucose tolerance test.
Fasting blood glucose test
- In diabetes, blood glucose levels remain elevated even on an empty stomach.
- To conduct this study, you will be asked to take nothing except water for 8-10 hours. Usually, this study is carried out in the morning, after a night's sleep, before breakfast, and you will be warned that the last meal should be no later than 8 hours before the study. For example, if the study is conducted at 8 am, then the last meal should be no later than 12 am.
- If there is no diabetes, the plasma glucose level does not exceed 6.1 mmol / l.
- If fasting plasma glucose level is equal to or higher than 7.0 mmol / l, then it is suspicious of the presence of diabetes in the patient. To confirm the diagnosis, fasting plasma glucose should be repeated. And if in the repeated analysis of fasting plasma glucose is equal to or higher than 7.0 mmol / l, then the diagnosis of diabetes is considered to be established.
Blood sampling for glucose at random during the day
- This is the simplest method for the diagnosis of diabetes mellitus, which is usually used to diagnose type 1 diabetes mellitus or for severe symptoms in a person with suspected type 2 diabetes.
- In this test, blood glucose is examined at any time of the day and before the study there is no need to starve for 8 or more hours.
- If, at a randomly chosen time of day, the plasma glucose level was equal to or higher than 11.1 mmol / l and the person complained of symptoms typical for diabetes (frequent and abundant urination, thirst, unexplained weight loss and weakness), then the diagnosis is sugar diabetes is considered established.
Oral glucose tolerance test
- This is one of the generally accepted tests for the diagnosis of type 2 diabetes in people with latent diabetes. In its name there are two words that are not quite common for everyday speech: "oral" means nothing more than substance intake ("lane" - through and "oral" - mouth) and "tolerance" translated into Russian means "sustainability". So, if the entire phrase in the title is translated into ordinary Russian, then this is "a test of resistance to glucose, taken by mouth". In essence, this test determines the extent to which blood glucose rises when a person drinks a certain dose of it (75 grams). If the blood glucose in this test rises above the norm, then the person is not tolerant to it (unstable), as he has diabetes.
- The test is often used in mass screening of the population for latent diabetes of the second type. In addition, it is used for the diagnosis of latent diabetes mellitus type 2 in people with normal fasting blood glucose level, but with risk factors for diabetes (obesity, age older than 45 years, etc.).
- To conduct this test, you will be asked to eat nothing during the night. Then in the morning, blood is taken on an empty stomach and after that you are invited to drink a certain amount of glucose pre-measured in the laboratory - usually a glass of very sweet liquid with 75 g of glucose. 2 hours after taking glucose, blood is taken again.
If the plasma glucose level before glucose ingestion is equal to or higher than 7 mmol / l and / or 2 hours after glucose ingestion is higher than or equal to 11 mmol / l, then the diagnosis of type 2 diabetes is considered established, regardless of whether the symptoms of diabetes mellitus or not.
Diagnosis of diabetes by A1c level
There is such a substance in the blood, which is called glycated hemoglobin and is abbreviated to HbA1c or A1c. Its name can be not remembered, it is enough to remember how it is written in abbreviated form.
The higher the blood glucose level, the higher the A1c level. And at the same time, its level reflects the average value of blood glucose over the last 2-3 months. This is not accidental, since A1c is a hemoglobin that is irreversibly associated with glucose - the higher and longer it is raised, the more hemoglobin is associated with it. From here and the name - glycated, that is connected with glucose.
Given this close relationship between blood glucose levels and A1c, more recently, prominent diabetologists suggested using the A1c test to diagnose type 2 diabetes. This diagnostic method has not yet been applied in Russia and other European countries, but has been adopted in the United States. And, most likely, in the near future it can be recommended for general use as an alternative method for blood glucose to diagnose type 2 diabetes, although it does not completely replace the diagnosis of diabetes with blood glucose. So, with some anticipation of events for Russia and Europe, we consider the recommended criteria for the diagnosis of diabetes according to A1C by the American Diabetes Association:
- The blood for the study is taken from the finger or vein.
- A1c is measured in percent, which shows how much of your hemoglobin is associated with glucose. For example, if A1c = 8%, then this means that 8% of hemoglobin is associated with glucose. By the way, it binds to glucose even if it does not exceed normal values and therefore cannot be zero.
- Normally, A1c does not exceed 6.5%, otherwise a diagnosis of type 2 diabetes is made. That is, the diagnosis is simpler and more convenient compared to a blood glucose test — for example, you do not need to fast for 8–10 hours or take glucose and then wait for 2 hours for a second blood glucose test.
Categories of high risk of diabetes
In diabetology, that is, the science of diabetes, is also considered such a thing as "the risk of developing diabetes." It applies to people who have a higher chance of getting type 2 diabetes than the general population. First of all, this applies to those surveyed for blood glucose, in which its level, on the one hand, is higher than the norm, and on the other, below the level characteristic of diabetes. These can be three situations:
- Fasting plasma glucose is above normal (≥6.1 mmol / l), but below 7 mmol / l. This condition is called "impaired fasting glucose" or abbreviated NGN.
- On an empty stomach, the plasma glucose level is normal, but 2 hours after administration of glucose, it is above normal, but not at the level characteristic of diabetes, that is, within 7.8–11.0 mmol / l. This condition is called "impaired glucose tolerance" or NTG for short.
- The subject may have a combination of NGT + NTG. In this case, this state is still referred to as NTG. If your blood plasma glucose level is in one of these three ranges, some endocrinologists may tell you that you have "prediabetes", and others that you have "early carbohydrate metabolism disorders," but none of them should say that you have diabetes. So far you have only an increased risk of developing diabetes mellitus type 2 and if you take active measures to prevent it, then everything can fully normalize.
In connection with the introduction in the diagnosis of diabetes mellitus A1c, proposed and for this parameter criteria for an increased risk of developing diabetes mellitus type 2. If the level of A1c was in the range of 5.7-6.4%, then the risk of developing type 2 diabetes increases by 25-50%. And therefore, you need to start to urgently apply the measures of its prevention.