Diabetic kidney disease, also known as diabetic nephropathy, is a complication of type 1 and type 2 diabetes and a primary cause of chronic kidney disease globally. The condition is characterized by a progressive loss of kidney function over time. This decline in the kidneys’ ability to perform their necessary functions can eventually lead to kidney failure.
How Diabetes Affects the Kidneys
The kidneys contain millions of small filtering units called nephrons, each with a cluster of tiny blood vessels known as a glomerulus. Persistent high blood sugar (hyperglycemia) forces these filters to work harder, a state called hyperfiltration. Over time, this increased workload, combined with high blood pressure, damages the structures of the glomeruli.
High glucose levels lead to the glycosylation of proteins, where sugar molecules attach to proteins, causing cellular damage in the kidney. This leads to an expansion of material between cells and a thickening of the glomerular basement membrane. These structural changes impair the glomeruli’s ability to filter waste effectively.
A primary consequence of this damage is the leakage of protein, particularly albumin, from the blood into the urine, a condition called albuminuria. This process is sometimes compared to a damaged coffee filter that allows coffee grounds to pass through. The presence of albumin in the urine is one of the first detectable signs of diabetic kidney disease. As the damage progresses, the kidneys’ filtering capacity, measured as the glomerular filtration rate (GFR), begins to decline.
Symptoms and Diagnosis
In its initial stages, diabetic kidney disease progresses silently for years with no noticeable symptoms, which is why regular screening is necessary for anyone with diabetes. As kidney function deteriorates, symptoms may appear. These can include swelling (edema) in the legs, ankles, feet, or hands, an increased need to urinate, and persistent fatigue.
Later-stage symptoms may include nausea, vomiting, and a loss of appetite. High blood pressure that is difficult to control is also a common sign.
Diagnosis relies on two primary tests. A urine test checks for albumin, specifically using the urine albumin-to-creatinine ratio (uACR) to measure how much is being lost. A blood test determines the estimated Glomerular Filtration Rate (eGFR), which assesses how efficiently the kidneys filter waste. An eGFR below 60 ml/min/1.73m² suggests kidney damage.
Managing Diabetic Kidney Disease
Slowing the progression of diabetic kidney disease centers on controlling blood sugar and blood pressure. Maintaining target blood glucose levels is measured by the HbA1c test, which reflects average blood sugar over several months. Each 1% reduction in HbA1c can significantly reduce the risk of microalbuminuria.
Blood pressure control is also a priority. Medications such as angiotensin-converting enzyme (ACE) inhibitors and angiotensin II receptor blockers (ARBs) are prescribed. These drugs have a protective effect on the kidneys by reducing pressure within the glomeruli and are used even in patients without high blood pressure. The goal is to keep blood pressure below 130/80 mmHg.
Dietary adjustments are part of management. A healthcare provider may recommend a diet low in sodium to help control blood pressure and reduce fluid retention. As the disease progresses, limiting protein, potassium, and phosphorus may be necessary to decrease the workload on the kidneys.
Regular physical activity helps control both blood sugar and blood pressure. Quitting smoking is advised, as it can worsen kidney damage and increase cardiovascular risk. Maintaining a healthy weight through diet and exercise also helps reduce stress on the kidneys.
Advanced Stages and Complications
Progression of diabetic kidney disease can lead to end-stage renal disease (ESRD), or kidney failure, where the glomerular filtration rate falls below 15 ml/min/1.73m². At this stage, the kidneys have lost most of their ability to function. Waste products and excess fluid build up in the body, requiring renal replacement therapy to sustain life.
One primary treatment for ESRD is dialysis, a procedure that artificially removes waste products and excess fluid from the blood. The two main types are hemodialysis and peritoneal dialysis. In hemodialysis, blood is pumped to an artificial kidney machine and then returned to the body. Peritoneal dialysis uses a special fluid introduced into the abdomen to absorb waste from blood vessels in the abdominal lining.
A kidney transplant is another treatment option for ESRD, involving the surgical implantation of a healthy kidney from a deceased or living donor. A successful transplant can offer a more active life with fewer dietary restrictions compared to dialysis. However, it requires surgery and lifelong medication to prevent the body from rejecting the new organ.