Diabetes affects millions of people worldwide and is one of the leading causes of chronic kidney disease. Over time, persistently high blood sugar levels can cause damage to the small blood vessels, affecting the organ's ability to filter waste and excess fluid from the bloodstream.
While many patients with diabetes place their focus on managing their blood sugar levels, fewer understand how this condition can silently damage the kidneys. In order to take measures to prevent kidney damage, it is important to recognise the early warning signs and seek medical care when necessary.
How Does Diabetes Affect the Kidneys?
The kidneys contain millions of tiny filtering units called nephrons. Each nephron has a cluster of blood vessels known as a glomerulus, which filters waste and excess fluid from the blood.
When blood sugar levels remain elevated over time, they increase pressure within these filtering units and damage the blood vessel walls. This damage makes the vessels thicker and less efficient at filtering waste. High blood sugar also causes inflammation in kidney tissues, further reducing their ability to clean the blood effectively.
As the damage progresses, the kidneys begin to leak protein into the urine—a key sign of declining kidney function. Without proper management, this gradual deterioration can eventually lead to acute kidney injury or even chronic kidney disease.
Approximately 4 out of 10 people with diabetes will develop diabetic kidney disease (DKD), also known as diabetic nephropathy. This makes diabetes one of the leading causes of kidney failure globally.
Stages of Diabetic Kidney Disease (DKD)
Diabetic kidney disease usually progresses gradually over several years. The condition is typically classified into five stages based on kidney function, measured through blood tests that determine the glomerular filtration rate (GFR).
Stage 1: Hyperfiltration:
At this stage, the kidneys show signs of damage but continue to filter waste effectively. The GFR remains at 90 or higher, which is considered healthy. There are usually no noticeable symptoms, though small amounts of protein (albumin) may begin to appear in the urine.
Stage 2: Mild Kidney Damage:
The kidney function begins to decline slightly, with a GFR between 60 and 89. Like stage 1, symptoms remain uncommon, but protein leakage in the urine may persist or increase slightly. Ongoing monitoring and strict management of blood sugar and blood pressure remain important to slow disease progression.
Stage 3: Moderate Kidney Damage:
Stage 3 marks moderate loss of kidney function, with a GFR between 30 and 59. As the kidneys' filtering ability declines, waste products and fluid begin to accumulate in the body. This can lead to symptoms such as fatigue, swelling in the hands and feet and changes in urination patterns or appearance.
Stage 4: Severe Kidney Damage:
By stage 4, kidney function is severely reduced, with a GFR between 15 and 29. The kidneys struggle to remove toxins effectively, leading to more pronounced symptoms like persistent fatigue and significant swelling. A nephrologist will closely monitor your condition and help prepare for potential end-stage treatments, including dialysis or kidney transplantation.
Stage 5: Kidney Failure (End Stage Kidney Disease):
Stage 5 marks kidney failure, where the GFR drops below 15, and the kidneys can no longer sustain normal body function. Severe symptoms such as shortness of breath, confusion and muscle cramps may develop. Management typically involves dialysis (haemodialysis or peritoneal dialysis) or a kidney transplant to replace lost kidney function.
How to Lower the Risk of Kidney Disease If You Have Diabetes
Get Regular Kidney Check-Ups:
As kidney disease often develops without noticeable symptoms, annual blood and urine tests can detect early changes before serious damage occurs. Two key tests include:
- Urine Albumin-to-Creatinine Ratio (UACR): This urine test measures the amount of protein in the urine. Elevated protein levels may signal early kidney damage.
- Estimated Glomerular Filtration Rate (eGFR): This blood test estimates how well the kidneys filter waste from the blood. A lower eGFR may indicate reduced kidney function and help determine disease severity.
Make Healthy Lifestyle Changes:
Adopting kidney-friendly habits can significantly reduce the risk of developing or worsening diabetic kidney disease.
- Quit smoking: Smoking damages blood vessels throughout the body, including those in the kidneys, and accelerates kidney decline.
- Exercise regularly: Taking at least 30 minutes of moderate activity, such as brisk walking, most days of the week, can make a meaningful difference.
- Manage blood pressure: High blood pressure is a leading cause of kidney damage in people with diabetes. Work closely with your doctor to monitor these levels and adjust medications as needed.
- Adopt a kidney-friendly diet: Reduce salt and protein intake to help control blood pressure and prevent strain on the kidneys. Instead, focus on fresh vegetables, whole grains and lean proteins.
- Maintain a healthy weight: This minimises strain on the kidneys and improves overall metabolic health. If you are overweight, even modest weight loss can have significant benefits.
Take the Right Medications:
Angiotensin-converting enzyme (ACE) inhibitors and angiotensin receptor blockers (ARBs) are commonly prescribed to help lower blood pressure and reduce protein leakage in the urine. By controlling these factors, they help protect kidney function and slow disease progression.
However, it is important to avoid medications that may harm the kidneys. Overuse of non-steroidal anti-inflammatory drugs (NSAIDs) can worsen kidney function, especially in people with diabetes. Always consult your doctor before taking over-the-counter pain medications.
Protecting Your Kidneys When Living With Diabetes
Diabetes can have a gradual but serious impact on kidney health if not carefully managed. Over time, damage may silently build up before leading to permanent kidney disability. In order to decrease the chance of this happening, regular monitoring and early intervention are essential.
