Pars plana vitrectomy, glycemic control, and systemic adverse events in patients with diabetes mellitus: a retrospective cohort study

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Background The relationship between hemoglobin A1c (HbA1c), pars plana vitrectomy (PPV), and systemic health risks remains incompletely understood. We aimed to determine whether undergoing PPV is associated with increased risk of systemic adverse events in diabetic patients (Analysis 1) and whether higher HbA1c is associated with increased risk of systemic events among PPV patients (Analysis 2). Methods We conducted a retrospective cohort study using the TriNetX US Collaborative Network. In Analysis 1, adults with diabetes mellitus who underwent PPV were stratified by preoperative HbA1c (< 8.0 or ≥ 8.0) and propensity score matched to diabetic patients who attended an outpatient eye care visit and did not undergo PPV. We estimated 30- and 60-day hazard ratios (HRs) for mortality, stroke or transient ischemic attack, major cardiovascular event, hospitalization, and a composite outcome. In Analysis 2, all diabetic PPV patients were analyzed as a single cohort using Cox proportional hazards models to estimate the association between HbA1c, modeled continuously, and each systemic outcome. Results In Analysis 1, the PPV and outpatient visit cohorts each included 6,506 patients with HbA1c ≥ 8.0 and 10,559 patients with HbA1c < 8.0. Undergoing PPV was not associated with a significant increase in 30- or 60-day risk of any outcome across HbA1c strata. For the composite outcome, 30-day HRs were 1.09 (95% CI, 0.72, 1.63) among patients with HbA1c ≥ 8.0 and 1.16 (95% CI, 0.85, 1.58) for patients with HbA1c < 8.0. In Analysis 2, among 15,622 patients, HbA1c was not associated with increased risk of any systemic outcome; HRs ranged from 0.96 to 1.07 at 30 days and from 0.99 to 1.02 at 60 days. Conclusions In this study, undergoing PPV was not associated with increased short-term risk of systemic adverse events in diabetic patients, including those with elevated HbA1c. Similarly, higher preoperative HbA1c was not associated with increased systemic risk following PPV. These findings are reassuring regarding the short-term systemic safety of PPV in diabetic patients and support individualized perioperative risk assessment.