The Role of Baseline Traction and Diabetes Type in Predicting Recurrence After Vitrectomy for Proliferative Diabetic Retinopathy.

Purpose: To assess whether Type 1 diabetes mellitus (T1DM) was independently associated with 2-year postoperative recurrence after pars plana vitrectomy for proliferative diabetic retinopathy (PDR), or whether the crude association reflected differences in age and baseline traction severity. Patients and Methods: This secondary prognostic analysis used a previously reported retrospective registry of 608 eyes from 608 patients who underwent vitrectomy for PDR between January 2020 and May 2024. Diabetes classification and diabetes duration were newly extracted from medical records. The primary outcome was postoperative recurrence requiring clinical intervention, defined as the first occurrence of postoperative vitreous hemorrhage (VH) or tractional retinal detachment (TRD) within a truncated 24-month analysis window. Sequential Cox models assessed attenuation of the association between T1DM and recurrence after adjustment for age, traction severity, and clinical covariates. Fine-Gray models evaluated VH and TRD as competing failure modes. Results: Of 608 patients, 105 had T1DM and 503 had Type 2 diabetes mellitus. T1DM patients were younger and had a higher proportion of severe preoperative traction. Recurrence was more frequent in T1DM eyes than in T2DM eyes within 24 months (33.3% vs 22.3%; P=0.013). T1DM was associated with recurrence in the crude Cox model (HR=1.612; 95% CI, 1.103-2.356; P=0.014), but the association was attenuated after adjustment for age and traction severity and was not significant in the fully adjusted model (aHR=1.169; 95% CI, 0.688-1.985; P=0.564). Severe preoperative traction remained associated with recurrence (aHR=1.824; 95% CI, 1.155-2.882; P=0.010) and was specifically associated with TRD recurrence in competing-risk analysis (aSHR=4.871; 95% CI, 1.946-12.192; P<0.001). Conclusion: In this retrospective secondary analysis, the crude association between T1DM and 2-year postoperative recurrence was attenuated after adjustment for age and baseline traction severity. Severe preoperative traction showed a more consistent association with recurrence, particularly recurrent TRD, than diabetes type alone. Baseline traction severity may therefore be more informative for postoperative counseling and surveillance in this cohort. External validation is warranted.