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A normal urine albumin-to-creatinine ratio (UACR) can be reassuring in patients with type 2 diabetes. However, it does not always mean kidney function is stable. Some patients experience progressive kidney decline without developing elevated urinary albumin. This pattern is known as normoalbuminuric diabetic kidney disease, a form of kidney disease that can develop without elevated urine albumin levels.
New research published in Diabetes on October 21, 2026, suggests that several blood and urine biomarkers may reveal kidney injury that conventional albumin measurements fail to capture. These findings could eventually help clinicians identify higher-risk patients earlier, although the markers remain investigational.
Table of Contents
- Why Normal Albuminuria Can Miss Kidney Decline
- Research Findings: Four Biomarkers Associated With Kidney Risk
- Can Multiple Biomarkers Improve Kidney Risk Prediction?
- Clinical Implications and Future Research
- Conclusion
- Frequently Asked Questions
Why Normal Albuminuria Can Miss Kidney Decline
For years, UACR has been an important tool for detecting diabetic kidney disease. Elevated urinary albumin can signal damage to the kidneys' filtering system. However, kidney injury does not always follow this familiar pattern.
In some patients with diabetes, kidney function gradually declines even when their urine albumin-to-creatinine ratio remains below 30 mg/g. As a result, clinicians who focus primarily on albuminuria may underestimate kidney risk.
This distinction matters because kidney damage involves more than the filtering structures. Inflammation, injury to kidney tubules, tissue scarring, and impaired repair processes can also contribute to declining function. Furthermore, these processes may develop without substantial increases in urinary albumin.
Earlier research supports this concern. In the Joslin Kidney Study, approximately 6% of participants with type 2 diabetes, normal baseline estimated glomerular filtration rate (eGFR), and normal albuminuria experienced early progressive kidney decline.
Importantly, these findings do not make UACR unnecessary. Instead, they reinforce the value of assessing UACR alongside eGFR trends and other clinical risk factors.
Research Findings: Four Biomarkers Associated With Kidney Risk
A 2026 study led by Erik Moedt and colleagues examined protein biomarkers in people with type 2 diabetes and normal albuminuria. The analysis used stored samples from participants in the Canagliflozin Cardiovascular Assessment Study (CANVAS).
The analysis included 2,573 participants and evaluated a composite outcome involving sustained kidney function decline of at least 40%, kidney failure, or kidney-related death.
During follow-up, 53 participants, or 2.1%, experienced the composite kidney outcome. Interestingly, baseline UACR was not associated with this outcome in the study population.
In contrast, four biomarkers demonstrated independent associations with subsequent kidney events. These markers reflect biological processes that standard urine albumin testing may not fully capture.
TNFR-1, TNFR-2, KIM-1, and MMP-7
Tumor necrosis factor receptors 1 and 2 (TNFR-1 and TNFR-2) reflect inflammatory signaling that may contribute to kidney damage. Higher levels of these proteins were associated with increased kidney risk.
Kidney injury molecule-1 (KIM-1) is associated with injury to kidney tubular cells. Therefore, elevated KIM-1 may provide information about damage that urinary albumin measurements do not directly capture.
Matrix metalloproteinase-7 (MMP-7) is linked to changes in kidney tissue structure and processes involved in fibrosis. Its association with kidney outcomes suggests that structural changes may contribute to declining kidney function even when albuminuria remains normal.
Additionally, the researchers examined urinary epidermal growth factor relative to creatinine (uEGF/Cr), a potential indicator of the kidney's capacity for repair and regeneration.
Among participants who developed kidney events, TNFR-1, TNFR-2, and KIM-1 increased over time, while uEGF/Cr decreased. These differing patterns provide evidence that several biological processes may contribute to progressive loss of kidney function.
Can Multiple Biomarkers Improve Kidney Risk Prediction?
The findings raise an important question: Could combining biomarkers provide a clearer picture of kidney risk than UACR alone?
Each marker reflects a different aspect of kidney health. TNFR-1 and TNFR-2 relate to inflammation, KIM-1 reflects tubular injury, and MMP-7 is associated with tissue remodeling. Meanwhile, uEGF/Cr may offer information about regenerative capacity.
Together, these measurements could potentially identify changes that remain invisible to standard urine albumin testing. In particular, they may help characterize diabetic kidney disease without albuminuria, a condition that conventional risk assessment can overlook.
The researchers also examined changes in biomarker levels following treatment with canagliflozin, an SGLT2 inhibitor marketed as Invokana. Compared with placebo, canagliflozin reduced the rise in KIM-1, limited the decline in uEGF/Cr, and suppressed the increase in MMP-7 observed in the placebo group.
These results suggest that biomarkers may eventually help researchers understand treatment responses beyond changes in UACR. Furthermore, monitoring several markers could provide insights into inflammation, kidney tubular injury, and tissue repair during treatment.
However, important limitations remain. Only 53 participants experienced the composite kidney outcome, limiting the precision of risk estimates. In addition, an association between a biomarker and kidney decline does not prove that using the marker to guide treatment improves outcomes.
Before routine adoption, researchers must establish whether combining biomarkers meaningfully improves prediction beyond eGFR, UACR, and established clinical characteristics. They must also determine appropriate testing thresholds, costs, and clinical actions.
Clinical Implications and Future Research
For clinicians, the immediate lesson is not to replace established kidney screening methods. Instead, the research highlights the need to recognize patients whose kidney function declines despite normal urine albumin measurements.
Current KDIGO guidance on diabetes and chronic kidney disease supports comprehensive kidney assessment. The broader 2024 KDIGO chronic kidney disease guideline emphasizes evaluating kidney health using both UACR and eGFR.
Consequently, repeated eGFR measurements remain essential for identifying progressive kidney dysfunction. Clinicians should also consider blood pressure, glycemic control, medications, cardiovascular disease, and possible causes of kidney impairment unrelated to diabetes.
For eligible patients with established chronic kidney disease, evidence-based treatment remains central to slowing progression. SGLT2 inhibitors, including canagliflozin (Invokana), dapagliflozin (Farxiga), and empagliflozin (Jardiance), have demonstrated kidney benefits in appropriate populations.
Additional information is available in Diabetes in Control's coverage of SGLT2 inhibitors and kidney disease in type 2 diabetes.
Nevertheless, the new biomarker findings do not justify routinely ordering TNFR-1, TNFR-2, KIM-1, or MMP-7. Their usefulness for clinical decision-making still requires prospective validation.
Future studies should establish whether these markers improve patient outcomes, identify individuals who benefit from closer monitoring, or help guide treatment decisions. Researchers will also need to determine whether the additional information justifies the cost and complexity of testing.
Until then, clinicians should prioritize established kidney function testing and individualized risk management. A normal UACR should not override a concerning pattern of declining eGFR.
Conclusion
For clinicians treating patients with type 2 diabetes, declining kidney function despite normal urine albumin levels remains an important diagnostic challenge.
The latest findings suggest that TNFR-1, TNFR-2, KIM-1, and MMP-7 may identify kidney risk that UACR alone fails to capture. Moreover, changing levels of these proteins and uEGF/Cr may offer insights into disease progression and treatment response.
Although promising, these biomarkers are not ready to replace routine screening. For now, combining UACR with ongoing eGFR assessment and evidence-based care remains the most practical approach.
Ultimately, recognizing that kidney decline can occur without elevated albuminuria may help clinicians avoid overlooking patients who need closer evaluation and monitoring.
Frequently Asked Questions
What is normoalbuminuric diabetic kidney disease?
It describes kidney dysfunction in people with diabetes who have normal urinary albumin levels. Patients may experience reduced or declining eGFR despite UACR remaining below 30 mg/g.
Can diabetic kidney disease progress with normal UACR?
Yes. Kidney dysfunction can occur without elevated albuminuria. Therefore, clinicians should monitor eGFR alongside UACR rather than relying on urine albumin results alone.
Which biomarkers were associated with kidney decline?
The 2026 study identified TNFR-1, TNFR-2, KIM-1, and MMP-7 as independently associated with kidney outcomes. Researchers also observed changes in uEGF/Cr among participants who developed kidney events.
Should clinicians routinely order these biomarker tests?
Not currently. The findings are promising, but additional studies must establish their clinical usefulness, accuracy, cost-effectiveness, and value in guiding treatment decisions.
What should clinicians do when eGFR declines but UACR remains normal?
Clinicians should confirm the eGFR trend, evaluate possible causes, review medications and risk factors, and follow established kidney disease guidance. Specialist evaluation may be appropriate depending on the rate and severity of decline.
Research Reference
Moedt E, Ju W, Neuen BL, et al. Novel Protein Biomarkers to Monitor Kidney Function Decline and Treatment Response in Individuals With Normoalbuminuria and Type 2 Diabetes. Diabetes. Published online October 21, 2026. DOI: 10.2337/db26-0626.
This content is not medical advice. For any health issues, always consult a healthcare professional. In an emergency, call 911 or your local emergency services.