Combined stress hyperglycemia ratio and glycemic variability phenotypes with severe acute kidney injury after cardiac surgery across glucose metabolic states

Stress hyperglycemia ratio (SHR) and glycemic variability (GV) capture different aspects of acute glycemic disturbance, but their joint association with severe acute kidney injury (AKI) after cardiac surgery remains unclear. This retrospective MIMIC-IV cohort included adults undergoing cardiac surgery. GV was calculated from exactly the first three routinely collected glucose measurements obtained within 24 h after ICU admission; patients developing severe AKI during this period were excluded. Tertile-based SHR and GV thresholds defined four phenotypes. Severe AKI after 24 h was identified using serum creatinine and renal replacement therapy criteria. Multivariable regression, interaction, spline, and sensitivity analyses were performed. Among 2475 patients, 336 developed severe AKI. Neither SHR nor GV alone was independently associated with severe AKI. Phenotype associations differed by glucose metabolic status (P for interaction < 0.001). In normal glucose regulation, High SHR/High GV was associated with higher odds of severe AKI than Low SHR/Low GV (adjusted OR 2.59, 95% CI 1.27–5.10; P = 0.007). Adding the phenotype increased the AUC from 0.766 to 0.801 ( P = 0.029). Combined SHR/GV associations varied across glucose metabolic states. Findings in normal glucose regulation were exploratory and require independent validation.