Diabetes and kidney dysfunction: how it is connected, causes of the problem, symptoms, diagnosis, treatment

Many people know that kidneys often suffer from diabetes: every third patient diagnosed with type 1 diabetes and only 5% of people with type 2 diabetes. This suggests that the problem is very urgent. This organ ensures the functioning of the entire body, and diabetes mellitus (DM) very quickly destroys the kidneys. Without treatment, such disorders can cause death. Therapy should be carried out under the close supervision of the attending physician.

How does diabetes affect the kidneys?

Kidneys in diabetes are considered target organs. Diabetes mellitus affects various organs and systems, and it is possible that it also affects renal epithelial cells.

Even with ongoing drug therapy, severe diseases develop. Among the most common pathologies are:

• diabetic nephropathy.
  Elevated glucose levels lead to damage to the structural elements responsible for filtration processes, as well as the vascular component. As a result, a steadily progressing process leads to kidney failure due to diabetes mellitus, which leads to the death of the patient. Therefore, in diabetes mellitus, kidney complications in the form of nephropathic changes are especially dangerous. A special diet reduces the likelihood of kidney failure in diabetes mellitus, since a reduced amount of glucose inhibits the development of destructive processes;
• pyelonephritis. The development of a nonspecific inflammatory process with damage to kidney structures, which is of bacterial origin, occurs quite often in type 2 or type 1 diabetes. This is due to decreased immunity and high levels of glucose, which creates a breeding ground for microbes;
• urolithiasis.
  Disruption of metabolic processes leads to an increased risk of oxalate formation in the kidneys. Stones injure the renal epithelium. Destructive changes in the organ due to the formation of stones lead to impaired blood circulation, as well as trophic processes with a deterioration in absorption function. Due to a decrease in the body's sensitivity to aldosterone, salt accumulation occurs during hyperglycemia.

Are all people with diabetes at risk of kidney damage?

We know from experience that not all diabetics suffer from kidney disease.
Not every person with chronically poorly controlled diabetes develops kidney disease, which in turn sometimes affects even relatively well-treated patients. An explanation for this phenomenon was provided by genetic studies, which show that there are individuals in whom the development of nephropathy is genetically determined and, conversely, individuals whose genes protect against the disease. The results of these studies suggest that there is indeed a link between genetics, diabetic nephropathy and high blood pressure.

More simply, diabetic nephropathy is the result of poor diabetes control and a genetic predisposition to hypertension. Immunogenicity methods are not yet so advanced that it is known how it is possible to determine who is at risk for diabetic nephropathy. However, it can be assumed that the danger of diabetes with poor glycemic control is present if there is a lack of treatment for high blood pressure. From this follow therapeutic strategies and procedures.

Causes of kidney disease in diabetes

Kidney damage in established diabetes mellitus is one of the most common complications of the disease. This is explained by the filtration of blood with a high glucose content and damage to its organ structures.

Risk factors for the development of nephropathy include irreducible hyperglycemia, lipid metabolism disorders, arterial hypertension, bad habits and excess body weight.

Gradually, damaged filter elements turn into scars. As a result, kidneys in diabetes cannot perform their functions due to a decrease in the volume of tissue that is responsible for purifying the blood.

As the process progresses, intoxication develops, which can cause kidney failure. At this stage, the patient requires timely therapy, including the use of medications, as well as dialysis.

In the absence of timely treatment, the filtration function is disrupted due to damage to the tissue barrier, which is manifested by the ingress of protein into the urine, which should not normally be present in the biological fluid.

Decreased organ function can lead to the development of terminal conditions. The most dangerous course of pathology caused by diabetes mellitus is associated with the addition of arterial hypertension. In this case, the diabetic kidney experiences an imbalance in the tone of the afferent and efferent arterioles.

An increase in pressure and destruction of the vascular wall against the background of a hyperglycemic state leads to metabolic disorders with a number of pathological changes in biochemical processes.

Glycosylated protein contained in kidney membranes increases the activity of enzymes that cause an increase in the permeability of the vascular wall and the formation of free radicals. This mechanism accelerates the development of diabetic nephropathy.

Diagnosis of the disease

CKD can be diagnosed using the following methods:

• Clinical urine analysis. Albuminuria is diagnosed (the appearance of albumin, blood proteins, in the urine).
• Excretory urography. X-ray of the kidneys with the introduction of a contrast agent allows you to assess the size and location of the organ and urinary tract.
• Ultrasound of the kidneys. Prescribed for kidney stones, cysts are diagnosed.
• Needle biopsy of the kidney. A piece of the organ is taken for analysis and examined for the presence of pathological changes.
• Computed tomogram (CT). Evaluates the condition of blood vessels, the presence of tumors and stones.

Symptoms of pathology development

There are 5 clinical stages of nephropathy:

1. Asymptomatic course. There are no symptoms, pathology is detected using additional diagnostic methods.
2. The stage of initial changes in the structure of the kidneys. Glomerular filtration rate begins to gradually deteriorate.
3. Prenephrotic course. An increase in microalbumin concentration does not lead to the development of clinically significant proteinuria. Some patients may experience symptoms of hypertension.
4. Nephrotic course. An increase in blood pressure is observed constantly. Protein is detected in the urine, and a blood test reveals an increase in erythrocyte sedimentation rate and cholesterol. The filtration function is reduced, and patients experience swelling.
5. Uremic course. A decrease in the filtration function leads to the fact that creatinine and urea are contained in the blood in high concentrations. A decrease in protein leads to the development of edema and a critical increase in blood pressure.

Diabetic nephropathy may not manifest itself for a long time and may not affect the patient’s quality of life. In this case, its symptoms are completely absent.

At the first and second stages, minor changes in well-being are noted. Against the background of diabetes, the kidneys begin to hurt, and discomfort appears in the lumbar region. Patients do not experience the development of edema syndrome. In this case, there is no protein in the urine.

At the third stage, there are no obvious manifestations of nephropathy. When contacting a specialist, patients may complain of a gradual increase in blood pressure. Taking medications leads to a temporary decrease. Protein is detected in the urine.

At the fourth stage of the pathological process, arterial hypertension becomes stable and is accompanied by tachycardia. During the day, swelling occurs with typical localization on the face and limbs.

Increasing fatigue and headaches lead to disruption of general well-being with increased fatigue and decreased performance. The pain syndrome also extends to the abdominal cavity and chest.

The fifth stage of nephropathy is characterized by constant swelling of the face and accumulation of fluid in the abdominal cavity, loss of appetite, diarrhea, vomiting and nausea.

The volume of daily urine gradually decreases. Weakness and fatigue limit the patient's activity, making it difficult to perform usual activities.

Changes in the glomerular apparatus begin several years after the patient is diagnosed with diabetes. Your health may deteriorate sharply in 10-15 years.

The severity of symptoms will depend on how developing diabetes mellitus affects the kidneys.

What are kidneys?

The kidneys are a paired organ that performs the following functions:

• Filter waste from the blood that ends up in the urine;
• Maintain blood pressure, partly by the amount of water removed from the blood into the urine, and partly by hormones involved in controlling blood pressure;
• They produce the hormone erythropoietin, which stimulates the bone marrow to produce red blood cells;
• They help maintain the correct balance of salt and chemicals in the blood, an incorrect ratio of which can cause diseases of various organs and systems of the body. The most important are potassium, sodium, calcium and phosphorus salts.

The kidneys are located in the upper part of the abdominal cavity, behind the intestines and on the sides of the spine. Above them are the adrenal glands. Each bud is the size of a large orange and shaped like a bean.

The kidneys work as follows. A large artery called the renal artery supplies blood to each kidney. In the outer part of the kidney, the artery branches into small capillaries, which permeate each kidney in a network. In the outer part of the organ, these capillaries unite and form structures called glomeruli. Each glomerulus acts as a filter: their structure is designed in such a way that waste and some water and salt pass through them into small vessels called tubules. At the same time, the normal number of red blood cells and proteins in the blood is maintained. Urine flows through the tubules into the renal pelvis, and from there through the ureter into the bladder.

Each glomerulus and tubule is part of a nephron. Each kidney contains about a million nephrons. As waste and water pass through the tubules, a very complex process occurs to form the contents of this fluid. For example, some water and salt may be sent back into the circulatory system, depending on the water and salt content of the blood. This process of fine-tuning the composition of blood and urine, as well as the ratio of water and salts, occurs in small vessels near the tubules called the loop of Henle.

The liquid resulting from this process and remaining at the end of each tubule is called urine. It flows further into wider passages called collecting ducts, which enter the inside of the kidney called the renal pelvis. Next, the urine passes into the ureter, which connects the kidneys to the bladder, collects in it and remains until the person goes to the toilet.

Blood filtered by the kidneys is collected in large veins called renal veins. They transport blood purified by the kidneys back into the bloodstream.

Diagnostic methods for diabetes mellitus

After examining the patient, the doctor prescribes a series of diagnostic tests. If renal failure in diabetes is detected in the early stages, this will significantly improve the prognosis.

The main diagnostic methods used are:

• general clinical blood test;
• general clinical urine analysis;
• blood biochemistry with determination of albumin and creatinine levels;
• Zimnitsky's test;
• Reberg-Tareev test, which allows you to measure glomerular filtration rate.

The tests allow us to judge the severity of the disease and the effectiveness of the therapy.

Why the main threat to the kidneys is high sugar

Excess glucose in the blood has a toxic effect on various systems of the body, because glucose molecules bind to proteins and disrupt their functioning.
This is called a glycosylation reaction. Before scientists carefully studied this reaction, it was assumed that the cause of diabetic nephropathy was hyperfiltration, i.e. acceleration of glomerular filtration and increased load on the kidneys.

Having read the previous section of the article, you now know that the acceleration of glomerular filtration is not a cause, but a consequence. The real cause of kidney failure is the toxic effect that high blood sugar has on cells.

In the process of using food proteins, the body produces waste products - urea and ammonia, which contain nitrogen. Back in the mid-twentieth century, scientists suggested that the glomerular filtration rate in the kidneys increases due to the need to cleanse the blood of urea and ammonia.

Therefore, diabetic patients were and are still recommended to eat less protein to reduce the load on the kidneys. But a study by Israeli scientists showed that in healthy people without diabetes, the glomerular filtration rate in the kidneys is the same on a protein-rich diet and on a vegetarian diet.

Over the years, it has been discovered that the incidence of kidney failure among vegetarians and meat eaters is not statistically different. It has also been proven that an increased glomerular filtration rate is neither a necessary nor a sufficient condition for the development of diabetic nephropathy.

A Harvard study found the following. A group of laboratory rats had their blood sugar maintained at about 14 mmol/L.

Diabetic nephropathy quickly developed in each of these rats. If more protein was added to their diet, the development of kidney failure accelerated.

The neighboring group of rats had blood sugar at 5.5 mmol/l. They all lived normally.

None of them developed diabetic nephropathy, regardless of how much protein they consumed. It is also interesting that the rats' kidney function recovered within a few months after their blood sugar dropped to normal.

The modern theory of the development of diabetic nephropathy is that several factors simultaneously affect the capillaries in the glomeruli of the kidneys. This is the glycation of proteins due to high blood sugar, also antibodies to glycated proteins, excess platelets in the blood and blockage of small vessels with blood clots.

At the early stage of diabetic kidney damage, the power of the negative electrical charge in the pores of the capillaries decreases. As a result of this, negatively charged proteins of the smallest diameter, in particular albumin, begin to leak into the urine from the blood.

If a urine test shows that it contains albumin, then this is called microalbuminuria and means an increased risk of kidney failure, heart attack, or stroke.

Kidney treatment for diabetes

Treatment of kidneys for type 1 or 2 diabetes mellitus is carried out with the help of medications. The selection of drugs is carried out after assessing the clinical symptoms, determining the stage of the disease, as well as possible organ dysfunction.

The following medicinal groups are used:

• ACE inhibitors. Hypertension medications are designed to stabilize blood pressure, which can worsen nephropathy. A positive effect on the functioning of the cardiovascular system and prevention of the progression of nephropathy is achieved through long-term and regular use of ACE inhibitors.
• insulin preparations. These drugs act on the cause of the pathology and reduce blood sugar levels. This slows down the destruction of the kidney filter and blood vessels. The dosage is selected by the doctor in accordance with the level of glucose in the blood serum;
• hypoglycemic agents. Taking tablet medications allows you to control your blood sugar. The mechanism of action is similar to insulin. During treatment, you need to measure glucose levels, and if necessary, the dosage is reduced or increased.

Dialysis or kidney transplantation is used in the absence of effect from the drug therapy and a decrease in filtration function, which does not reach a value of 15 ml/min/1.73 m2.

In this case, replacement therapy is indicated, which is aimed at stabilizing the patient’s well-being.

In addition, it should be used for hyperkalemia that is not amenable to medication and fluid retention in the body. Transplantation is necessary if visible symptoms of protein-energy malnutrition occur.

The hemodialysis procedure involves filtering the blood using an artificial kidney machine. It is recommended to carry it out up to three times a week.

In addition to detoxification, it helps reduce blood pressure levels. Dialysis is carried out with extreme caution due to the possible drop in blood pressure and infection.

Treatment of nephropathy is carried out in inpatient or outpatient settings. Outpatient treatment is carried out in the initial stages of the disease, as well as with satisfactory test results.

In this case, you should regularly visit a specialist while taking medications to assess the dynamics of the pathological process. In severe cases, if kidney damage is accompanied by severe dysfunction of the organ, treatment is carried out in a hospital setting.

Diabetes and kidneys: what you need to remember

If there are problems with the kidneys, blood tests for creatinine and urine tests for microalbuminuria can detect them early. If you start treatment on time, it significantly increases the chances of success. Therefore, the tests described here (will open in a separate window) must be taken regularly once a year. Consider using a low-carb diet to normalize your blood sugar. Read more in the article “Diet for kidneys with diabetes.”

Many diabetics who have high blood pressure benefit from limiting salt in their diet in addition to medications. Try reducing your intake of sodium chloride, i.e. table salt, and see what results you get. Each person has their own individual sensitivity to salt.

Another complication, diabetic neuropathy, can damage the nerves that control the bladder. In this case, the function of emptying the bladder is impaired. In the urine that remains all the time, an infection can multiply, damaging the kidneys. At the same time, in diabetics who have managed to normalize their blood sugar, neuropathy most often turns out to be reversible, that is, it goes away completely.

If you have difficulty urinating or other signs of a urinary tract infection, contact your doctor immediately. These problems can seriously accelerate the development of kidney complications in diabetes.

Diet for diabetic nephropathy

A diet for the kidneys in diabetes forms the basis of the therapy, since adherence to the diet and the inclusion of healthy foods in the diet helps stabilize the patient’s condition and reduces the risk of complications.

Diet principles:

• refusal to eat sweets. Confectionery products and products containing a high percentage of sugar lead to a deterioration in the patient’s condition due to an increase in blood glucose levels;
• salt restriction. Food containing large amounts of salt can lead to fluid retention in tissues, increasing the load on the kidneys;
• eating small portions of food. It is important for patients to reduce the size of portions, since a large amount of food eaten at one time leads not only to an increase in the load on the digestive tract, but also to a rapid increase in blood glucose levels. It must be taken into account that in diabetes mellitus the production of digestive enzymes is impaired. The average serving size is 200-300 grams;
• balanced menu. Excluding fatty, fried, as well as smoked and flour products from the diet for diabetes can lead to a lack of energy and a deterioration in the patient’s well-being. Therefore, it is important to balance the menu at the stage of preclinical changes, before the development of irreversible consequences.

A daily meal plan includes eating enough carbohydrates, proteins and fats. The body must receive various microelements, especially with chronic renal failure.

At this stage, the renal barrier begins to allow useful substances to pass through, removing them from the body with urine.

The main indicator when choosing safe food for patients with diabetes is the measurement of the glycemic index. It reflects the amount of carbohydrates that are taken in and broken down in the body and affect glucose levels.

The main task of the diet for nephropathy is the selection of foods with a low glycemic index. They take longer to digest and do not lead to a rapid increase in glucose levels. Preference should be given to:

• fruits and berries, such as various types of currants, green gooseberries, apples and citrus fruits;
• vegetables, including green beans, eggplants, onions, lentils, peas and various types of cabbage.
• pearl barley and barley, wild rice, buckwheat and bulgur;
• dairy products without added sugar and leaven.

Patients with this pathology need to consume foods whose glycemic index does not exceed 50 units. The consumption of foods such as fruits or berries that have not undergone heat treatment should occur primarily in the morning.

Due to the loss of valuable fiber during mechanical processing, adding freshly squeezed juices or purees to the daily menu is not recommended.

Diet for kidney failure: menu, nutritional principles

The main feature of the diet for kidney failure is its high calorie content. The purpose of nutrition in this case is to ensure the penetration of useful substances into the human body - this will inhibit the breakdown of proteins, which provokes an increase in the level of urea in the blood.

What is allowed and what is prohibited for sick people to eat? What food will help restore kidney function faster?

General principles

The diet for kidney failure does not involve losing weight, so the daily menu will contain oil, fats and even sweets.

The basic rules of the diet for chronic renal failure are as follows:

• 20-70 g of proteins per day;
• increased consumption of fats and carbohydrates;
• saturating the diet with fruits and vegetables;
• salt and liquid control.

In case of diabetes mellitus, which often causes chronic renal failure, sweets should be kept to a minimum. In other cases, sugar consumption is allowed.

If the patient is obese, a diet high in high-calorie foods may worsen weight problems. In this case, it is necessary to increase the amount of vegetables eaten in order to prevent feelings of hunger. It is recommended to saturate your diet with cabbage - fresh and pickled, spinach, cucumbers, tomatoes, green peas. They promote quick saturation.

Diet for the initial stage of chronic renal failure

The diet for chronic renal failure at the initial stage (grade 1) of the disease involves a slight restriction of proteins - 1 g per 1 kg of weight. Priority is given to plant proteins, which are found in abundance in foods such as:

• bread;
• vegetables;
• cereals;
• nuts;
• beans;
• peas.

The fact is that the metabolic products of these proteins are easier to remove. Plus they contain a lot of alkaline compounds that prevent acidosis.

For patients with chronic renal failure, it is important to contain high-calorie foods with fats and carbohydrates in their diet. Of these, the healthiest ones are those found in fruits and vegetables, and they should be included in recipes for breakfast, lunch and dinner. However, if you have diabetes, it is forbidden to eat bananas, watermelons, and sweet apples.

Salt for chronic renal failure does not need to be severely limited. You cannot add salt while cooking, but you can consume about 5–6 g during the day. For patients with polyuria (increased urine output), a different rule applies. They can increase the daily dosage of salt to 5-6 g for every liter of urine excreted.

Daily fluid intake for chronic renal failure should be 500 ml more than the volume of urine excreted over the previous day. This is necessary to display all metabolic products. Otherwise, they will accumulate, which will lead to poisoning of internal organs.

One day every week should be a fasting day. Suitable for this purpose:

• watermelons;
• potato;
• apples;
• pumpkin.

If you have diabetes, you cannot unload on watermelons. It is recommended to choose unsweetened apples.

Nutrition in advanced stages of chronic renal failure

The diet for renal failure if the disease reaches an advanced stage will be slightly different. Protein consumption must be seriously limited - to 20-24 g per day, and up to 75% of this volume should be animal food: eggs, fish, meat and milk. This way, the body will receive the required amount of amino acids. Although dairy products are not prohibited for diabetes, you can drink them only if you receive approval from a doctor, otherwise the patient’s condition may worsen.

To prevent food from seeming bland, the use of spices, herbs, and lemon juice is allowed. Spicy seasonings, in particular mustard and pepper, should be excluded from the diet, which is especially important for diabetes. If chronic renal failure occurs without swelling and high blood pressure, salt is allowed, but not more than 3 g per day.

The daily volume of fluid should be 0.5 liters more than the amount of urine excreted over the previous day. You can drink not only pure water, but also mineral water and diluted juices. Soups should be taken into account in the final volume of liquid consumed. For diabetes mellitus accompanying chronic renal failure, it is recommended to use a rosehip decoction rich in vitamins.

All food must be boiled, but fish and meat can be fried afterwards. In this case, a taboo is placed on drinks and foods that cause irritation to the kidneys:

• strong tea;
• coffee;
• alcohol;
• cocoa;
• chocolate;
• hot spices;
• pickles;
• broths for meat and fish;
• mushrooms.

With concomitant diabetes mellitus, it is important to maintain a fractional diet - you should eat small portions 5-6 times a day. This will relieve the feeling of hunger.

When preparing recipes, you should keep in mind that the daily dose of calories should be 2000–2800 Kcal. This means that you can eat 120–130 g of fat and 230–280 g of carbohydrates every day.

Prevention of kidney disease in diabetes mellitus

Since the kidneys are especially severely affected in diabetes mellitus, the task of patients and specialists who monitor them is to preserve the organ.

Diabetics need to regularly monitor their blood pressure. Other preventive measures include:

• regular monitoring of glucose levels;
• assessment of laboratory parameters;
• mandatory intake of medications prescribed by a doctor;
• treatment of concomitant pathologies.

It is important for patients to undergo regular kidney examinations, since early detection of changes will allow therapy to be adjusted and the development of complications to be prevented.

Prevention

To avoid complications, the patient should adhere to the following recommendations:

• quit smoking;
• follow a diet with a limited amount of animal fats and proteins;
• exclude foods high in salt from the diet;
• measure blood pressure in the morning and evening;
• at least once a year (and if possible, every 6 months) take a urine test for timely detection of pathologies;
• refuse medications that can cause disorders of the genitourinary system;
• control blood glucose levels.

Regular physical activity – running, cycling, walking in the fresh air – helps normalize metabolism. It will help strengthen the body's defenses and increase resistance to infections.

Treatment

At an early stage of the disease, clinical recommendations are prescribed to the patient by a therapist and an endocrinologist. If a patient has a lesion above stage 3, he must be observed by a nephrologist on an ongoing basis.

The main goals in the fight against nephropathy are inextricably linked with the treatment of diabetes in general. These include:

1. decreased blood sugar levels;
2. stabilization of blood pressure;
3. normalization of cholesterol levels.

Medications to combat nephropathy

ACE inhibitors have worked well
for the treatment of high blood pressure during diabetic nephropathy .
They generally have a good effect on the cardiovascular system and reduce the risk of late-stage nephropathy.

Sometimes patients experience a reaction to this group of drugs in the form of a dry cough , then preference should be given to angiotensin-II receptor blockers. They are a little more expensive, but have no contraindications.

ACE inhibitors and angiotensin receptor blockers cannot be used simultaneously.

If GFR decreases, the patient needs to adjust the dose of insulin and glucose-lowering drugs. This can only be done by a doctor based on the overall clinical picture.

Hemodialysis: indications, effectiveness

Sometimes drug treatment does not give the desired results and GFR becomes below 15 ml/min/m2, then the patient is prescribed renal replacement therapy.

Her testimony also includes:

• a clear increase in potassium levels in the blood, which is not reduced by medication;
• fluid retention in the body, which can cause serious consequences;
• visible symptoms of protein-energy malnutrition.

One of the existing methods of replacement therapy, along with peritoneal dialysis and kidney transplantation, is hemodialysis.

To help the patient, he is connected to a special device that performs the function of an artificial kidney - it cleanses the blood and the body as a whole.

This treatment method is available in hospital departments, since the patient must remain near the device for about 4 hours 3 times a week.

Hemodialysis allows you to filter the blood, remove toxins and poisons from the body, and normalize blood pressure.

Possible complications include decreased blood pressure and infection.

Contraindications for hemodialysis are: severe mental disorders, tuberculosis, cancer, heart failure, stroke, some blood diseases, age over 80 years. But in very severe cases, when a person’s life hangs in the balance, there are no contraindications for hemodialysis.

Hemodialysis allows you to temporarily restore kidney function; in general, it prolongs life by 10-12 years. Most often, doctors use this treatment as a temporary treatment before a kidney transplant.

Diet and prevention

A patient with nephropathy is obliged to use all possible levers for treatment. A properly selected diet will not only help with this, but will also improve the overall condition of the body.

To do this, the patient should:

• consume minimal protein foods (especially of animal origin);
• limit the use of salt during cooking;
• if the level of potassium in the blood is low, add foods rich in this element to the diet (bananas, buckwheat, cottage cheese, spinach, etc.);
• refuse spicy, smoked, pickled, canned foods;
• drink high-quality drinking water;
• switch to fractional meals;
• limit foods high in cholesterol in your diet;
• give preference to the “right” carbohydrates.

A diet low in protein is basic for patients with nephropathy. It has been scientifically proven that large amounts of protein in the diet have a direct nephrotoxic effect.