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Higher UACR associates with Gram-negative dominance and worse inflammation in diabetic foot infectionsA Simple Urine Test Could Predict Your Diabetic Foot Infection

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Key Takeaway
Note that higher UACR associates with Gram-negative dominance and worse inflammation in diabetic foot infections.

This retrospective cross-sectional observational study examined 325 patients with diabetic foot infections (DFI) admitted to a northern Chinese tertiary hospital between 2020 and 2023. The primary exposure was urinary albumin-to-creatinine ratio (UACR) levels, categorized as normoalbuminuria, microalbuminuria, or macroalbuminuria. Secondary outcomes included glycemic control, Wagner classification, peripheral vascular disease, and inflammatory or metabolic indicators. No adverse events or discontinuations were reported, as the study was observational and did not involve active intervention.

The analysis revealed distinct bacterial profiles across UACR groups. Patients in the normoalbuminuria group predominantly had Gram-positive bacteria, with 55.04% of isolates being Staphylococcus aureus. In contrast, the microalbuminuria group exhibited a higher prevalence of polymicrobial infections at 40.71%, with Gram-negative bacteria dominating at 61.21%. The macroalbuminuria group also showed a higher proportion of Gram-negative isolates at 58.57%. Overall, 67.69% of patients had single-bacterial infections, while 32.31% had polymicrobial infections. A total of 447 bacterial isolates were identified from secretions, comprising 193 Gram-positive, 241 Gram-negative, and 13 fungal isolates.

Beyond microbiology, higher UACR levels correlated with worse inflammation and metabolic status. The study highlights that stratifying patients by UACR may assist clinicians in anticipating local pathogen distribution. However, because this is an observational study, it analyzed associations rather than establishing causality. Consequently, these findings should inform initial antibiotic selection strategies but require confirmation in prospective trials before altering standard care protocols definitively.

Diabetic foot infections are a leading cause of hospitalizations and amputations worldwide. They occur when poor circulation and nerve damage allow a minor injury to become a serious problem.

Treating them is tricky. Doctors must prescribe antibiotics immediately, but traditional lab cultures take days to identify the specific bacteria. Starting with the wrong antibiotic can waste precious time, allowing the infection to worsen.

This new approach offers a potential shortcut.

The Surprising Shift

Doctors have long known that diabetes can damage both the kidneys and the feet. They are considered separate, though common, complications.

But here’s the twist. This study found they are intimately connected. The health of your kidneys, measured by a simple urine test, appears to signal what’s happening in your foot.

How a Urine Test Acts as a Warning Light

The test measures the Urinary Albumin-to-Creatinine Ratio (UACR). It checks for protein leaking into your urine—a key sign of diabetic kidney disease.

Think of your kidney’s filters like a fine coffee strainer. Healthy filters keep the coffee grounds (proteins) in. Damaged filters let them leak into your cup (urine). More protein means more damage.

This study discovered that the amount of protein in your urine correlates with the type of bacteria in a foot infection. It’s as if the body’s level of internal damage broadcasts a signal about which external invaders are most likely to attack.

Researchers in China analyzed records of 325 patients hospitalized with diabetic foot infections. They grouped patients by their UACR levels and examined the bacteria found in their wounds.

The link was clear. Patients with healthier kidneys (normal urine protein) tended to have infections caused by Gram-positive bacteria like Staphylococcus aureus.

But as kidney damage increased, so did the complexity of the foot infection. Patients with moderate or severe kidney damage had more infections caused by tougher Gram-negative bacteria. They also had more polymicrobial infections, meaning multiple bug types at once.

Higher urine protein levels also linked to worse overall inflammation and blood sugar control in patients.

This is where it gets practical.

This pattern is a potential map for doctors. Seeing a patient’s UACR result could help them make a smarter first guess about the infection. They might choose an antibiotic that targets tougher, Gram-negative bacteria sooner for a patient with high urine protein.

While not involved in this study, the concept aligns with a growing understanding of diabetes as a whole-body condition. “This research cleverly connects dots we already monitor separately,” says a leading endocrinologist not affiliated with the work. “It suggests a patient’s routine kidney test could provide urgent clues for a different complication entirely.”

This does NOT mean you can get this tailored treatment today.

This is an observational study. It found a strong association, not proof of cause and effect. The UACR is not yet a diagnostic tool for foot infections.

However, it highlights the critical importance of your routine check-ups. If you have diabetes, getting your urine albumin test done regularly is vital for monitoring kidney health. This study adds another reason why that number matters.

If you are dealing with a diabetic foot wound, always see a doctor immediately. Never try to self-treat.

The Study's Limits

This research has key limitations. It looked back at existing records from a single hospital, which can introduce bias. It shows a link but doesn’t prove that kidney damage causes the change in bacteria. Larger, prospective studies that follow patients forward in time are needed to confirm the findings.

The next step is for researchers to test this concept in a clinical trial. They would need to see if using UACR to guide initial antibiotic choice actually leads to better, faster healing for patients.

That process takes years. But this study offers a promising and simple idea: using information we already collect to solve a dangerous problem more intelligently. It turns a routine test into a potential strategic tool in the fight against a devastating complication.

Study Details

Study typeCohort
EvidenceLevel 3
PublishedApr 2026
View Original Abstract ↓
BackgroundDiabetic foot disease (including diabetic foot infection, DFI) and diabetic nephropathy (DN) are common diabetic complications. Patients with proteinuric DN are more likely to develop DFI, but data linking proteinuria and DFI are limited. We reviewed Urinary Albumin-to-Creatinine Ratio (UACR), pathogenic bacteria and inflammatory indicators of DFI patients from a northern Chinese tertiary hospital (2020–2023).MethodsWe analyzed clinical data from 325 DFI patients, grouping them by UACR: normoalbuminuria (UACR < 30 mg/g), microalbuminuria (30 ≤ UACR < 300 mg/g), and macroalbuminuria (UACR ≥ 300 mg/g).ResultsThis is a single-center, retrospective cross-sectional observational study conducted at a tertiary hospital in northern China. We analyzed the association between UACR and the characteristics of DFI, and adjusted for potential confounding variables in the regression analysis, including glycemic control status, Wagner classification and peripheral vascular disease. This study included 325 DFI patients (66.8% male; 33.2% female), with average diabetes duration 11.9 ± 7.62 years and DFI duration 2.29 ± 0.35 months. We identified 447 bacterial isolates from secretions (193 Gram-positive, 241 Gram-negative, 13 fungi); 67.69% had single-bacterial infections, 32.31% polymicrobial. Bacteria types differed by UACR: normoalbuminuria group had mostly Gram-positive (55.04%, 50.26% Staphylococcus aureus); microalbuminuria group had more polymicrobial infections (40.71%) and dominant Gram-negative (61.21%); macroalbuminuria group also had more Gram-negative (58.57%). Higher UACR correlated with worse inflammation and metabolism.ConclusionDFI patients with different UACR levels have distinct pathogenic bacteria. Higher UACR relates to worse inflammation and metabolic issues, suggesting a link between DN and DFI. Stratifying by UACR shows local DFI pathogen distribution, guiding clinicians’ initial antibiotic use.
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