Diabetes mellitus, also known as diabetes, is an umbrella term for metabolic disorders characterized by elevated blood glucose levels. Over the long term, these increased blood sugar levels can have far-reaching consequences for the entire body. Most commonly, long-standing, inadequately controlled diabetes leads to diabetic nephropathy—kidney damage induced by diabetes. Depending on the type of diabetes, between 20% and 40% of all people with diabetes develop chronic kidney disease over time.
Why diabetes attacks the kidneys
Kidney damage is caused by damage to the blood vessels caused by the increased sugar levels in the blood. This damage is called microangiopathies. They can also occur in other parts of the body and lead to further diabetes-related complications. In the eye, retinal damage—diabetic retinopathy—can develop and may lead to blindness. In the foot, in addition to the blood vessels, nerves are often affected as well, which can result in poorly healing wounds as well as movement and sensory disturbances. This condition is known as diabetic foot syndrome.
In the kidney, the so-called glomeruli—i.e., the renal corpuscles—are damaged. They are an important component of the kidney and consist of a tuft of small blood vessels. Their function is similar to that of a filter: some substances are filtered and excreted in the urine, while others are retained in the blood and remain in the body. Due to elevated blood sugar levels, the blood vessels of the renal corpuscles are gradually damaged; the glomeruli can no longer perform their filtering function properly. As a result, substances that should actually remain in the body are released into the urine—most notably proteins such as albumin. In people with diabetes, microalbuminuria in the urine can then be detected as one of the first signs of diabetic nephropathy. If the damage goes unnoticed, kidney function may continue to decline over time, in the worst case progressing to kidney failure requiring dialysis.
Detect microalbuminuria early
Because the kidney can silently tolerate impairment for a long time, regular screening is crucial. The current National Care Guideline for Type 2 Diabetes recommends an annual determination of the albumin-to-creatinine ratio (UACR) in a spot urine sample starting at diagnosis for type 2 diabetes, and for type 1 diabetes no later than five years after initial diagnosis, supplemented by measurement of the estimated glomerular filtration rate (eGFR) from blood. Values between 30 and 300 mg albumin per gram creatinine are considered moderately elevated; values above that are considered markedly elevated and require further evaluation.
What treatment can achieve today
Treatment of diabetic nephropathy has changed significantly in recent years. The foundation remains individually tailored blood glucose and blood pressure control, supplemented by ACE inhibitors or angiotensin receptor blockers to attenuate the renin–angiotensin system. A true paradigm shift has been brought about by SGLT2 inhibitors: in many patients, they slow the progression of kidney disease independently of their effect on blood glucose. In addition, finerenone has been available for several years as a non-steroidal mineralocorticoid receptor antagonist that can further reduce albuminuria and protect kidney function. The combination of these drug classes is now anchored in the relevant guidelines.
What patients can do themselves
For prevention, regular monitoring of glucose levels in blood and urine is recommended, as well as the screening for microalbuminuria offered as part of preventive care. In this way, uncontrolled blood sugar levels or the first signs of diabetic nephropathy can be detected and treated at an early stage. In addition, blood pressure control, weight management, avoiding nicotine, and a diet tailored to kidney function play an important role.
Sources
German Medical Association, KBV, AWMF – National Care Guideline for Type 2 Diabetes, Version 3.0 (2024): register.awmf.org/de/leitlinien/detail/nvl-001
KDIGO – 2024 Clinical Practice Guideline for the Evaluation and Management of Chronic Kidney Disease: kdigo.org/KDIGO-2024-CKD-Guideline.pdf
German Diabetes Association (DDG) – Practice recommendation “Diabetes and Nephropathy” (2023): ddg.info/Praxisempfehlungen_Diabetes-und-Nephropathie
Robert Koch Institute – Diabetes Surveillance: Diabetic kidney disease: diabsurv.rki.de/3-26_Diabetische_Nierenerkrankung
German Diabetes Association – Diabetes Health Report 2025: ddg.info/Gesundheitsbericht_2025
German Society of Nephrology (DGfN) – Information for patients: dgfn.eu/patienten
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