Diabetes can impact many parts of the body, and the kidneys are especially susceptible to damage over time. This complication, diabetic kidney disease, develops gradually and often without early symptoms, making regular screening a fundamental part of diabetes care. Prompt detection of kidney problems allows for interventions that can slow the progression of damage and prevent more serious health issues.
The primary tool for this detection is a urine test that measures the albumin to creatinine ratio (ACR). This test identifies a specific protein in the urine that serves as an early indicator of kidney stress, enabling timely adjustments to treatment plans.
The Role of the ACR Test in Diabetes Management
The albumin to creatinine ratio (ACR) test is a non-invasive urine screening that measures two substances: albumin and creatinine. Albumin is a protein abundant in the blood that nourishes tissues and transports substances throughout the body. Healthy kidneys have a filtration system that keeps albumin in the bloodstream while removing waste.
When kidneys are damaged, this system can be compromised, allowing albumin to leak into the urine, a condition called albuminuria. Creatinine is a waste product from muscle metabolism that is filtered by the kidneys at a fairly constant rate. The concentration of urine can vary depending on a person’s fluid intake, which can affect the amount of albumin detected.
Measuring creatinine helps to correct for these variations in urine dilution. By calculating the ratio of albumin to creatinine, the ACR test provides a standardized measurement that is more accurate than measuring albumin alone. This ratio offers a reliable picture of how much albumin is passing into the urine, regardless of its concentration.
How Diabetes Affects Kidney Function
The kidneys contain millions of tiny filtering units called glomeruli. Each glomerulus acts as a microscopic sieve, processing blood to remove waste while retaining components like proteins. In people with diabetes, chronically high blood glucose can damage these delicate structures.
Over time, elevated blood sugar harms the small blood vessels within the glomeruli, causing them to thicken and scar. This damage makes the filters “leaky,” impairing their ability to hold back larger molecules like albumin, which then escapes into the urine. In the initial stages, the kidneys might overcompensate by filtering blood faster than normal, a state known as hyperfiltration that can add more stress.
High blood pressure (hypertension) often accompanies diabetes and accelerates this kidney damage. The increased force of blood flow can cause the fragile kidney vessels to narrow and weaken, reducing their filtering efficiency. This creates a damaging cycle, as kidney damage itself can contribute to a rise in blood pressure. The combined effect of high blood sugar and high blood pressure is a primary driver of diabetic kidney disease.
Interpreting ACR Test Results
ACR test results are reported as a ratio of milligrams (mg) of albumin per gram (g) of creatinine. A positive result is confirmed with repeat tests over three to six months to rule out temporary factors that might affect albumin levels, such as a fever or intense exercise.
A normal ACR value is less than 30 mg/g. This result indicates that a very low amount of albumin is passing into the urine, suggesting the kidney’s filtration system is functioning properly. Regular annual screening is still recommended to monitor for any future changes.
A result between 30 and 300 mg/g is classified as moderately increased albuminuria. This range is the earliest indicator of diabetic kidney disease and provides an opportunity to implement or intensify treatments to protect the kidneys. This stage was formerly called microalbuminuria.
An ACR value greater than 300 mg/g is categorized as severely increased albuminuria. This level signifies more advanced kidney damage and a higher likelihood of the disease progressing toward kidney failure. Patients with these results require close management of their diabetes and blood pressure to slow the decline in kidney function. This stage was previously known as macroalbuminuria.
Managing Kidney Health with Diabetes
Managing diabetic kidney disease focuses on slowing its progression and preserving kidney function. The most impactful intervention is maintaining stable blood glucose levels. Consistently keeping blood sugar within a target range, often monitored with the A1C test, directly reduces stress on the glomeruli.
Controlling blood pressure is also important for kidney protection. For people with diabetes and albuminuria, specific blood pressure medications are often prescribed. Angiotensin-converting enzyme (ACE) inhibitors and angiotensin II receptor blockers (ARBs) are used because they lower blood pressure and have a direct protective effect on the kidneys by reducing pressure inside the glomeruli.
Lifestyle and dietary adjustments also support kidney health. These actions support overall cardiovascular health, which is closely linked to kidney function.
- Eating a diet lower in sodium to help control blood pressure
- Moderating protein intake, if recommended by a physician
- Engaging in regular physical activity
- Maintaining a healthy weight
- Avoiding smoking
Consistent monitoring is part of long-term management. Annual ACR testing allows healthcare providers to track albumin in the urine, while regular blood tests measure the estimated glomerular filtration rate (eGFR) to evaluate how well the kidneys are filtering waste. Together, these tests provide a comprehensive picture of kidney health.