The difference in scotopic and photopic pupil responses: a potential indicator for long-term glycemic management

Diabetic autonomic neuropathy manifests in pupillary dynamics, often serving as a subtle precursor to systemic complications. Therefore, quantitative biomarkers that can effectively index disease chronicity and autonomic status—independent of glycemic control—are required for precise monitoring. Hence, we evaluated the diagnostic utility of the pupil diameter (PD) difference under varying lighting conditions in a cohort of diabetic patients and non-diabetic controls. We employed high-resolution pupillometry to quantify pupillary responsiveness and assessed the association between PD difference, glycated hemoglobin (HbA1c), and disease duration. We observed a significant attenuation in the PD difference in the diabetic group (0.94 ± 0.44) compared to controls (1.21 ± 0.48), with high statistical significance. Data from receiver operating characteristic (ROC) analysis suggested that PD difference meets the performance criteria for identifying established disease duration (>1 year), indicating that quantitative pupillometry provides a viable clinical endpoint for assessing the chronicity of diabetes and its associated autonomic neuropathy.