Purpose <p>To investigate the relationship between pupillary response and diabetic characteristics in cataract patients and explore whether impaired pupillary function may impact cataract surgical outcomes and visual recovery in diabetic patients.</p> Methods <p>This prospective study included 362 participants (133 diabetic patients and 229 controls) who underwent cataract surgery. Diabetic patients were stratified by disease duration (≤ 1 year, 1–10 years, &gt; 10 years). Pupil parameters and Visual quality metrics including higher-order aberrations (HOA), Strehl ratio (SR), and area ratio (AR) were evaluated using the OPD-Scan III aberrometer preoperatively and at 1&#xa0;day, 1 week, and 1 month postoperatively.</p> Results <p>Scotopic pupil diameter (PD) demonstrated a progressive decline with increasing diabetes duration. Patients with duration &gt; 10 years showed significantly smaller scotopic pupils compared to controls (<i>p</i> &lt; 0.0001) and shorter-duration subgroups (<i>p</i> &lt; 0.01). PD difference deteriorated progressively in patients with duration &gt; 1 year (<i>p</i> &lt; 0.0001). Linear regression revealed that each 1% increase in HbA1c was associated with a 0.10&#xa0;mm decrease in PD difference (β=-0.103, <i>p</i> &lt; 0.001) and reduced scotopic PD (β=-0.112, <i>p</i> = 0.025). Postoperative visual quality parameters (HOA, SR, AR) showed comparable improvement between diabetic and control groups at all time points (<i>p</i> &gt; 0.05), with diabetes duration showing minimal influence on outcomes.</p> Conclusion <p>Diabetic patients exhibit reduced pupillary sensitivity, particularly affecting scotopic pupil dilation, significantly associated with elevated HbA1c levels and longer diabetes duration. Postoperative improvements in visual quality of diabetic patients are comparable to those of non-diabetic patients, supporting use of functional intraocular lenses.</p>