Choroidal microvascular heterogeneity across non-autoimmune type 2 diabetes mellitus subtypes defined by beta-cell...

To investigate the intergroup differences in choroidal thickness (CT), choroidal vascularity index (CVI), and choroidal vascular volume (CVV) across non-autoimmune type 2 diabetes mellitus (T2DM) subtypes defined by beta-cell function and insulin resistance.

This cross-sectional study enrolled 22 healthy controls (22 eyes) and 85 T2DM patients (85 eyes). T2DM patients were categorized into 4 groups using K-means clustering: Severe Insulin-deficient Diabetes (SIDD) =22, Severe Insulin-resistant Diabetes (SIRD)=26, Mild Obesity-related Diabetes (MOD)=16, and Mild Age-related Diabetes (MARD)=21. CT, CVI, CVV were measured by widefield swept-source optical coherence tomography angiography (WSS-OCTA) across three concentric annular regions(0 - 10 mm, 10 - 15 mm, and 15 - 20 mm), subdivided into 12 sectors. Linear mixed-effects and multivariate regression models were constructed to evaluate intergroup differences.

Compared with the control group, both CT and CVV decreased significantly in most of the 12 analyzed regions across all T2DM groups, whereas the MOD and SIRD groups exhibited no statistically significant global changes. In contrast, CVI exhibited pronounced spatial and subtype-specific heterogeneity. In the SIDD group, CVI decreased in most regions, with significant reductions in the nasal sector of the 0 - 10 mm annulus (P < 0.01]), and in the nasal and inferior sectors of the 10 - 15 mm annulus (P < 0.01] and -0.065 (P < 0.01). Conversely, the SIRD group demonstrated a widespread increase in CVI, with significant increased in the nasal (P < 0.05), superior (P < 0.05), and temporal (P < 0.05]) sectors of the 15 - 20 mm annulus.

Compared with CT and CVV, CVI shows the highest spatial heterogeneity. This indicates that divergent metabolic drivers may exert opposing effects on choroidal vascular remodeling. This subtype-specific characterization enhances our understanding of diabetic choroidopathy pathophysiology and holds potential for guiding personalized screening and therapeutic strategies.