Early detection and therapy play an essential role in diabetic nephropathy. This is because if the kidney disorder is detected too late, it can become chronic. Kidney damage in diabetics can be prevented or treated very effectively if control measures (good blood glucose control, optimal blood pressure, control of microalbumin levels) and adequate treatment are taken. However, if kidney damage is noticed too late, it cannot be reversed and inevitably leads to kidney failure. Diabetic nephropathy is one of the most common secondary diseases of diabetes. Diabetes type 1 and type 2 patients are equally affected with a frequency of 20 to 40 percent. The disease of the kidney now represents the most common cause of permanent kidney function failure in Germany, accounting for about 35%.
What is the role of the kidneys?
The kidneys have important functions to perform in our body. They detoxify the body from waste products produced in metabolism, control fluid and electrolyte balance, the amount and composition of blood, and blood pressure. In addition, the kidneys ensure that there are always enough red blood cells in the blood. In simple terms, the filtering task of the kidneys takes place in two steps: First, the blood is filtered in the so-called renal corpuscles. However, many other substances that the body needs also pass through the fine pores of the renal corpuscles along with the waste products. Therefore, a second step follows, namely the recovery of substances that are valuable and vital for the body.
Causes of diabetic nephropathy
In people with diabetes – both type 1 and type 2 – persistently high blood glucose levels or genetic predisposition can cause changes in the small vessels of the kidney. The filtering capacity of the kidney decreases more and more and with it the detoxification capacity. This leads to a so-called diabetic nephropathy. But what promotes diabetic nephropathy? The following factors increase the risk of developing such kidney damage:
- High blood pressure (hypertension)
- Poor blood glucose control
- Long duration of diabetes, genetic predisposition
- High protein intake, elevated blood lipid levels.
- Cigarette smoking
Diabetic nephropathy: symptoms
Diabetics themselves do not notice when their kidneys are damaged over time, because they do not feel pain and the urine does not change visibly. It is only at an advanced stage, after several years, that noticeable symptoms may occur. These include:
- Anemia (anemia)
- Fatigue, exhaustion and poor performance.
- Headache
- Itching
- Weight gain
- Water retention (edema), especially in the legs.
- Foaming urine
- Nausea or vomiting
- High blood pressure
- Increased blood lipid levels
- Discoloration of the skin (milk coffee color)
- Disturbances in the water-salt balance
- Susceptibility to infection
Diagnosis of diabetic nephropathy
The earlier the disease is detected, the more effectively it can be prevented from worsening. Therefore, every diabetic should also pay attention to his kidneys. If diabetes is present, two values are checked regularly to diagnose diabetic nephropathy as early as possible: first, the albumin value in the urine and second, the creatinine value.
Control of urinary albumin excretion.
The first sign of incipient nephropathy is minute traces of protein in the urine. This is known as microalbuminuria (20-200 mg albumin/liter morning urine). It is therefore the most important factor for early detection of diabetic kidney disease. Urine albumin excretion should therefore be checked once a year in diabetics. In type 1 diabetics, this should be done from five years after the manifestation of diabetes, but in type 2 diabetics from the time of diagnosis. Even if there are no signs of diabetic nephropathy. Detection can be done easily and at an early stage using special test strips. The first morning urine is tested on three days within several weeks. For the diagnosis of nephropathy, a concentration of > 20 mg albumin/liter is required from at least two of the three morning urines.The next stage is characterized by a larger amount of protein in the urine, so-called macroalbuminuria (micros: small, low; macros: large, much). Once persistent macroalbuminuria (> 300 mg/l albumin/24 h urine) exists, the progression of kidney disease can in most cases only be contained by appropriate medication, and is therefore irreversible.
Elevated creatinine levels may indicate nephropathy
To diagnose kidney disease as early as possible, the filtering capacity of the kidneys should also be checked at regular intervals, ideally once a year. If kidney dysfunction is present, it is indicated by elevated levels of kratinine in the blood plasma and urine. Creatinine is a product of muscle metabolism. The more the detoxification capacity of the kidneys is impaired, the higher the creatinine. Together with creatinine level, body weight, age, and gender, the filtering capacity of the kidney is determined.
When newly diagnosed with diabetes, always check the kidneys as well
Especially in older people, elevated blood glucose levels often go undetected for a very long time, and the diagnosis of diabetes also often takes years. Therefore, when diabetes becomes known, it should always also be clarified whether the kidney function may already be impaired.
Consequences of diabetic nephropathy
The disease progresses through five stages, the last of which is chronic renal failure. Nearly one in three diabetic patients develops renal dysfunction of varying severity during the course of the disease. If left untreated, diabetic nephropathy can result in kidney failure in about one third of those affected. In Germany, several thousand new diabetic patients undergo dialysis every year. Diabetes mellitus is thus the most common cause of chronic kidney failure.
Therapy and treatment of diabetic nephropathy.
Appropriate therapeutic measures are already required at the stage of microalbuminuria to prevent the transition to the chronic, i.e. irreversible, form of kidney damage. These include the following measures:
- If diabetic nephropathy is already present, the control and documentation of microalbuminuria takes place more closely meshed than in the prophylactic examination for early diagnosis, about every three to six months.
- Diabetic patients with kidney disease should aim for the lowest possible blood pressure value (120/80 mmHg). Because: the lower the blood pressure, the better the kidney works. ACE inhibitors and angiotensin II antagonists have proved effective in this respect. Patients benefit from lower blood pressure not only by a slower progression of kidney disease, but also by a reduction in the frequency of strokes and heart attacks. The reason: high blood pressure is one of the most important risk factors for diseases and deaths of the heart and brain.
- The SGLT-2 inhibitor empagliflozin can also slow a progression of diabetic nephropathy. This drug is considered very significant for the treatment of diabetic kidney disease. SGLT-2 inhibitors reduce the uptake of carbohydrates in the blood, which is why less glucose is available for energy production. If there is no more glucose to metabolize, the body switches its metabolism and begins to use fat for energy. In this state of ketosis, the concentration of sodium ions and chloride ions is increased, which also reduces the back pressure in the renal corpuscles. This also reduces hyperfiltration of the kidney. Medical experts assume that this effect of empagliflozin alone slows the progression of diabetic nephropathy.
- Optimally adjust blood sugar and check the long-term setting on the basis of the HbA1c value (below 7.0 percent or below 53 mmol/mo).
- Reduce the risk of infection of the urinary tract and pay attention to close-meshed ophthalmological controls.
- Smoking and alcohol consumption should be avoided.
- The reduction of excess weight is an important therapeutic measure. Even a small weight loss can cause a significant improvement in blood pressure and metabolic control. In losing weight can further help:
- An active lifestyle with plenty of exercise can help keep blood pressure levels low and reduce excess body weight.
- High fiber, balanced diet with plenty of vegetables.
Diet in diabetic nephropathy.
Dietary adjustment can have a great benefit not only for the course of the underlying diabetes itself, but also for diabetic nephropathy. The first step is to aim for a low blood glucose level and to counteract obesity and its sequelae. A low-salt diet and abstinence from nicotine are also recommended in any case. General recommendations that can positively influence the course of the disease should also be observed. In addition, those affected should avoid convenience foods and also instead of animal sources of fat, it is better to rely on wholesome, high-quality vegetable oils, nuts, and seeds.
Increased protein intake: advisable or not?
In the case of diabetic nephropathy, there are conflicting recommendations regarding protein intake. Often, diabetics adhere to the recommendation of increased protein intake, which can be helpful for weight loss. However, increased protein intake is also considered a risk factor for progression of diabetic nephropathy, as such also requires increased filtration capacity of the kidney. Therefore, it may also be useful for some patients to exchange high-protein, animal-based foods for low-protein, predominantly plant-based foods.
What should affected individuals eat?
For most patients, a kidney-friendly diet includes plenty of vegetables and plant-based foods in general, as these have a beneficial effect on blood sugar levels, counteract inflammation, and reduce the acid load in the body. Dialysis patients often benefit from a high-fat diet, as fats contain more energy and less potassium compared to carbohydrates. Since recommendations for optimal nutrition can vary greatly depending on the stage and course of the disease in diabetic nephropathy, it is usually a good idea to consult a trained nutritionist or dietician. For example, if nephropathy requiring dialysis is already present, the focus is often more on counteracting malnutrition.
