A new study reveals that B-type natriuretic peptide (BNP), a hormone typically used to detect heart failure, may be a powerful early warning sign for kidney disease in people with diabetes. Researchers found that BNP can predict kidney function decline independently of standard urine tests, and elevated levels combined with other markers identify patients at highest risk of kidney damage. This discovery could help doctors catch kidney problems before they become serious. What Is BNP and Why Does It Matter for Kidney Health? BNP is a hormone released by the heart when it experiences stress or strain. Doctors have used it for decades to diagnose heart failure, but recent research reveals it tells a broader story about organ health. The connection between heart and kidney function, known as cardiorenal interaction, means damage to one organ can accelerate deterioration in the other. When the heart struggles, the kidneys often follow, and vice versa. Researchers from Juntendo University in Japan wanted to understand whether BNP could predict chronic kidney disease (CKD) progression in people with diabetes, especially at levels that appear normal on standard lab tests. To answer this question, they followed 636 adults with diabetes for a median of 5.4 years, measuring BNP levels in blood samples and tracking kidney function using estimated glomerular filtration rate (eGFR), a standard measure of how well kidneys filter waste. How Did the Study Compare BNP to Traditional Kidney Tests? Currently, doctors rely on urine tests to assess kidney damage in diabetic patients. The most common markers include urinary albumin-to-creatinine ratio (UACR), urine protein-to-creatinine ratio (UPCR), and dipstick proteinuria. These tests measure protein leakage in urine, which signals kidney damage. However, the researchers wanted to know if BNP offered something these tests could not. The findings were striking. During the 5.4-year follow-up period, 74 participants experienced a 30% or greater decline in eGFR, indicating significant kidney function deterioration. BNP proved to be just as effective as traditional urine markers at predicting this decline. More importantly, BNP remained independently associated with kidney function decline even after researchers adjusted for UACR and other clinical factors. This means BNP provides prognostic information beyond what urine tests alone can offer. "BNP, which is widely used in routine clinical practice as an established biomarker for heart failure, is associated with the progression of CKD in individuals with diabetes even when BNP levels are within the normal range," explained Associate Professor Maki Murakoshi from Juntendo University. Associate Professor Maki Murakoshi, Department of Nephrology, Juntendo University Faculty of Medicine The research revealed a graded relationship between BNP levels and CKD risk. This means that as BNP levels increased, so did the risk of kidney disease progression, even within the range considered clinically normal. This is particularly important because it suggests doctors should not dismiss slightly elevated BNP levels in diabetic patients. Why Does Combining BNP With Urine Tests Work Better? The most powerful finding emerged when researchers looked at patients with elevations in both BNP and UACR. These individuals showed the highest risk of kidney function deterioration. This combination approach suggests that using both markers together could help doctors identify high-risk patients more accurately than either test alone. - BNP Advantages: Widely available in routine clinical practice, can identify risk even at normal levels, and provides information independent of urine protein markers. - UACR Advantages: Recommended by international guidelines as a reliable indicator of kidney damage and has been used successfully for decades to monitor kidney health. - Combined Approach: Using both BNP and UACR together improves risk stratification and helps identify patients who need earlier intervention to prevent progression to end-stage kidney disease. How Can Doctors Use This Information to Protect Kidney Health? The clinical implications are significant for the estimated 37 million Americans with chronic kidney disease. Early identification of high-risk patients allows doctors to intervene before kidney damage becomes irreversible. This is especially important for people with diabetes, since diabetic kidney disease is the leading cause of end-stage kidney disease worldwide. "Early identification of patients at high risk of CKD progression among individuals with diabetes, followed by appropriate therapeutic intervention, may help prevent not only progression to end-stage kidney disease but also the development of cardiovascular disease," noted Dr. Murakoshi. Associate Professor Maki Murakoshi, Department of Nephrology, Juntendo University Faculty of Medicine BNP testing could be particularly valuable in clinical settings where urine testing is not routinely performed or where patients have limited access to traditional screening. Since BNP is already measured in many routine blood tests for heart health, adding it to kidney disease risk assessment requires minimal additional effort or cost. Recent advances in kidney disease treatment, such as sodium-glucose cotransporter-2 inhibitors (SGLT2 inhibitors), have demonstrated protective effects for both the heart and kidneys. Identifying high-risk patients earlier means these protective therapies can be started sooner, potentially preventing years of progressive kidney damage. Steps to Take If You Have Diabetes and Kidney Concerns - Request Comprehensive Testing: Ask your doctor about checking both traditional kidney markers like UACR and BNP levels, especially if you have diabetes or a family history of kidney disease. - Monitor Blood Pressure and Blood Sugar: Keeping blood pressure below 130/80 mmHg and maintaining stable blood sugar levels are critical for slowing kidney disease progression in diabetic patients. - Discuss Treatment Options Early: If you are identified as high-risk, talk with your doctor about starting protective medications like SGLT2 inhibitors, which benefit both heart and kidney function. - Schedule Regular Follow-up Testing: Establish a routine schedule for kidney function monitoring, including eGFR and urine protein tests, to catch any changes early. The study, published in Diabetes Research and Clinical Practice in May 2026, represents an important step forward in understanding how to identify kidney disease risk earlier. By recognizing that a heart hormone can signal kidney trouble, doctors now have another tool to protect their diabetic patients from one of the most serious complications of diabetes.
