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.