The Association Between Preoperative HbA1c Levels and Postoperative Acute Kidney Injury in Isolated Coronary Artery Bypass Surgery

February 25, 2026 updated by: Osman Sila Aydin

"The Association Between Preoperative HbA1c Levels and Postoperative Acute Kidney Injury in Isolated Coronary Artery Bypass Surgery: A Prospective Observational Study"

Renal complications are frequently encountered in cardiac surgery and constitute significant causes of morbidity and mortality. They most commonly present in the form of acute kidney injury (AKI). The etiological factors of AKI include hemodynamic alterations, hemolysis and pigment nephropathy, inflammatory response and cytokine storm, ischemia-reperfusion injury, use of nephrotoxic agents, patient-related risk factors (advanced age, diabetes mellitus, preoperative renal insufficiency, congestive heart failure, hypertension, anemia), duration of surgery, and postoperative complications such as low cardiac output syndrome, sepsis, bleeding and reoperation, hypoalbuminemia, and fluid imbalance.

Previous studies have demonstrated several mechanisms through which elevated HbA1c levels may contribute to acute renal injury, including glomerular damage and hyperfiltration, endothelial dysfunction and microvascular injury, tubular damage, accumulation of glycation products and advanced glycation end products (AGEs), structural changes in blood vessels, and metabolic and systemic factors.

The evaluation of acute renal failure relies on fundamental scoring systems, biomarkers, and imaging modalities. Among the scoring systems, the most current and widely used is the KDIGO (Kidney Disease: Improving Global Outcomes) classification. According to the KDIGO definition, the diagnosis of AKI can be established when at least one of the following three criteria is met: an increase in serum creatinine of ≥0.3 mg/dL within 48 hours, an increase in serum creatinine to ≥1.5 times baseline within 7 days, or a urine output of <0.5 mL/kg/hour for more than 6 hours. AKI staging is performed based on these parameters.

Imaging modalities used in the assessment of renal function include renal ultrasonography (US), Doppler ultrasonography with measurement of the renal resistive index (RRI), renal MRI/MR angiography, and renal computed tomography (particularly CT angiography). RRI is a non-invasive, bedside-applicable method that provides direct information about renal vascular resistance by evaluating renal arterial flow patterns.

In our clinic, the rationale of the present study is to measure preoperative HbA1c and Doppler-derived RRI values in patients undergoing isolated coronary artery bypass surgery, and to evaluate their relationship with postoperative KDIGO classification and Doppler RRI values in order to gain insight into the development of AKI.

Study Overview

Status

Recruiting

Conditions

Study Type

Observational

Enrollment (Estimated)

200

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Locations

  • Turkey (Türkiye)
      • Bursa, Turkey (Türkiye)
        • Recruiting
        • University of Health Sciences, Bursa Yuksek Ihtisas Training & Research Hospital
        • Contact:

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

  • Adult
  • Older Adult

Accepts Healthy Volunteers

No

Sampling Method

Non-Probability Sample

Study Population

isolated coronary bypass graft surgery patients

Description

Inclusion Criteria:

  • Patients undergoing isolated elective CABG surgery
  • Patients with available preoperative and postoperative Doppler RRI measurements
  • Patients with available HbA1c data

Exclusion Criteria:

  • Patients with chronic kidney disease
  • Emergency surgeries
  • Redo/revision surgeries
  • Patients undergoing concomitant valve surgery
  • Presence of acute infection or sepsis
  • Advanced heart failure (EF <30%)
  • Requirement for intra-aortic balloon pump, pacemaker, or mechanical circulatory support
  • History of nephrectomy or single kidney
  • Preoperative serum creatinine >2.0 mg/dL
  • Pregnancy
  • Refusal to participate in the study

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

Cohorts and Interventions

Group / Cohort
isolated coronary bypass graft surgery patients

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
To evaluate the correlation between preoperative HbA1c Level, Doppler-Derived Renal Resistive Index (RRI), and development of acute kidney injury (KDIGO Criteria) after isolated coronary artery bypass grafting
Time Frame: Preoperative HbA1c Level Time Frame: Within 7 days prior to surgery Preoperative and Postoperative Renal Resistive Index (RRI) within 24 hours preoperatively and within 24 hours postoperatively KDIGO : 48 hours postoperatively,7 days postoperatively

Preoperative HbA1c Level; Glycated hemoglobin level will be measured from blood samples preoperatively.

Unit of Measure: Percentage (%) Measurement Tool:Standard laboratory high-performance liquid chromatography (HPLC) assay Preoperative and Postoperative Renal Resistive Index(RRI) RRI will be measured using Doppler ultrasonography from segmental or interlobar renal arteries.

Unit of Measure: Dimensionless ratio (RRI value) Measurement Tool: Doppler ultrasonography Normal Value Reference: RRI < 0.70 Outcome Measure Title: Incidence of Acute Kidney Injury (KDIGO Criteria) Acute kidney injury will be assessed according to KDIGO criteria. Unit of Measure: Incidence of AKI (% of patients meeting KDIGO criteria) AKI Stage (Stage 1-3 classification) Measurement Tool: Serum creatinine measurement (mg/dL) Urine output monitoring Definition: Increase in serum creatinine ≥0.3 mg/dL within 48 hours OR increase to ≥1.5 times baseline within 7 days OR urine output <0.5 mL/kg/hour for ≥6 hours
Preoperative HbA1c Level Time Frame: Within 7 days prior to surgery Preoperative and Postoperative Renal Resistive Index (RRI) within 24 hours preoperatively and within 24 hours postoperatively KDIGO : 48 hours postoperatively,7 days postoperatively

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
To evaluate the correlation between preoperative HbA1c Level, Doppler-Derived Renal Resistive Index (RRI), and intensive care unit length of stay after isolated coronary artery bypass grafting
Time Frame: Time Frame: From ICU admission after surgery until ICU discharge, up to one month
Length of Stay in the Intensive Care Unit Description:Duration of postoperative stay in the intensive care unit. Unit of Measure: Days Measurement Tool: Hospital electronic medical records
Time Frame: From ICU admission after surgery until ICU discharge, up to one month
To evaluate the correlation between preoperative HbA1c Level, Doppler-Derived Renal Resistive Index (RRI), and hospital length of stay after isolated coronary artery bypass grafting
Time Frame: Time Frame: From date of surgery until hospital discharge, up to 3 month
Total Hospital Length of Stay Description: Total duration of hospitalization following surgery. Unit of Measure: Days Measurement Tool: Hospital electronic medical records
Time Frame: From date of surgery until hospital discharge, up to 3 month

Other Outcome Measures

Outcome Measure
Measure Description
Time Frame
To evaluate the correlation between preoperative HbA1c level, Doppler-Derived Renal Resistive Index (RRI), and duration of mechanical ventilation after Isolated coronary artery bypass grafting
Time Frame: From ICU admission after surgery until successful extubation, up to one month

Duration of Postoperative Mechanical Ventilation Description: Total duration of invasive mechanical ventilation following surgery.

Unit of Measure: Hours Measurement Tool: Ventilator records and hospital electronic medical records
From ICU admission after surgery until successful extubation, up to one month

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Osman Sila Aydin

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

January 20, 2026

Primary Completion (Estimated)

August 30, 2026

Study Completion (Estimated)

August 30, 2026

Study Registration Dates

First Submitted

January 29, 2026

First Submitted That Met QC Criteria

February 25, 2026

First Posted (Actual)

March 3, 2026

Study Record Updates

Last Update Posted (Actual)

March 3, 2026

Last Update Submitted That Met QC Criteria

February 25, 2026

Last Verified

February 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • 2024-TBEK 2025/12-16

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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