Association Between Pancreatic β-Cell Function and Quantitative OCT Angiography Metrics in Patients with Type 2 Diabetes Without Clinical Diabetic Retinopathy

The study aims to investigate the relationship between pancreatic β-cell function and macular vascular structure and blood flow in patients with type 2 diabetes mellitus (DM) without clinical signs of diabetic retinopathy (DR). This prospective cross-sectional study enrolled 121 type 2 DM patients without clinical DR, representing a total of 240 eyes. The area under the C-peptide release curve (AUCC) derived from the oral glucose tolerance test, fasting serum C-peptide level and the updated Homeostasis Model Assessment (HOMA2) model were utilized to reflect pancreatic β-cell function. Insulin resistance (IR) was assessed by HOMA2 model. The macular vascular and blood flow parameters of patients were measured by optical coherence tomography angiography (OCTA). Separate Linear Mixed-Effects Models were employed to analyze the relationship between pancreatic β-cell function indicators and OCTA metrics. In separate multivariate models, AUCC, fasting serum C-peptide level, and HOMA2 estimates of β-cell function (HOMA2-B) each demonstrated a significant positive association with vessel density (VD) measures in the deep capillary plexus (DCP), including total DCP VD, parafoveal DCP VD, and perifoveal DCP VD. The impaired pancreatic β-cell function is significantly associated with adverse macular vasculature alterations, suggesting that these vascular changes may occur prior to the clinical manifestation of DR in patients with compromised β-cell function. β-cell function markers might help identify patients at risk of early subclinical retinal microvascular changes.