– In the context of diabetic nephropathy, both type 1 and type 2 diabetics initially experience an enlargement of the kidney and increased function, but this is not noticeable to the patient (stage 1).
– In the course of further years the microscopically fine thickenings of the tissue in the area of the renal corpuscles develop. The patient cannot subjectively detect these either (stage 2).
– Finally, the glomerules are so thickened that they can no longer perform their filter function. Small protein molecules (albumin) can pass through the filter and are lost to the body. Increased blood pressure values are often the first signs of kidney involvement at this stage (stage 3).
– In the further course of diabetic nephropathy, there is a continuous loss of protein, disturbance of the water and salt balance of the body and susceptibility to infection (stage 4).
– If, in addition, elevated blood lipid levels and fluid accumulation (edema) in the legs occur, this is known as nephrotic syndrome. Finally, metabolic waste products are no longer excreted. All kidney functions fail (terminal renal insufficiency) and the diabetic has to undergo dialysis (stage 5).
In older people, high blood sugar levels often persist for years without a diagnosis of diabetes mellitus. For example, diabetes mellitus can be diagnosed as a difficult-to-treat urinary tract infection, a poorly healing wound or routine blood sugar testing. In these cases, examinations of the kidney function should definitely be followed, as the kidneys may already be damaged by the long-term high blood sugar levels.
The excretion of glucose in the urine, which occurs when blood sugar levels are significantly elevated, with a strong feeling of thirst and a frequent urge to urinate, should not be interpreted as damage to the kidneys. Rather, glucosuria occurs when a certain threshold value for the reabsorption of glucose in the blood (renal threshold) is exceeded.