Purpose <p>To evaluate static and dynamic pupillometry parameters using Scheimpflug-based imaging in patients with type 2 diabetes mellitus (T2DM) and to correlate these parameters with the severity of diabetic retinopathy (DR) and glycemic control.</p> Methods <p>This was a cross-sectional, case–control study including 141 diabetic patients (282 eyes) and 91 age- and sex-matched healthy controls (182 eyes). Static pupillometry (SP) was assessed under scotopic, mesopic, and photopic conditions, while dynamic pupillometry (DP) measured pupillary diameter changes following a light stimulus. Pupillometry parameters were analyzed across different DR severity grades and correlated with metabolic markers including duration of diabetes, fasting blood sugar (FBS), postprandial blood sugar (PPBS), and HbA1c.</p> Results <p>Diabetic patients showed significantly reduced mean scotopic, mesopic, and photopic pupil diameters compared to controls (<i>p</i> &lt; 0.001). Dynamic pupillary diameter was significantly smaller in patients with moderate NPDR compared to those with no DR (<i>p</i> = 0.03). A significant negative correlation was observed between dynamic pupillary diameter and both FBS (r = –0.34, <i>p</i> = 0.009) and duration of diabetes (r = –0.41, <i>p</i> = 0.001).</p> Conclusion <p>Diabetic patients demonstrate impaired static and dynamic pupillary responses, which worsen with increasing DR severity and poorer short-term glycemic control. Scheimpflug-based pupillometry may serve as a non-invasive adjunctive tool for assessing early ocular changes in diabetes and monitoring disease progression.</p>