# Association of Serum Vitamin D With Macular Microvascular Structure in Type 2 Diabetic Mellitus Without Diabetic Retinopathy: A Cross‐Sectional Study

## TL;DR

This study found that low vitamin D levels in Type 2 diabetes patients are linked to changes in eye blood vessel structure, suggesting a possible link to future eye disease.

## Contribution

The study is the first to show a link between vitamin D deficiency and microvascular changes in the macula of Type 2 diabetes patients without retinopathy.

## Key findings

- Vitamin D deficiency was associated with reduced perfusion density in the superficial capillary plexus of the macula.
- The perifoveal area showed lower perfusion density in vitamin D deficient patients.
- Changes were most pronounced in the temporal-perifoveal region.

## Abstract

This study investigated the association of different serum vitamin D levels on macular microvascular structure in Type 2 diabetes mellitus (T2DM) patients without diabetic retinopathy (DR), utilizing optical coherence tomography angiography (OCTA).

A cross‐sectional observational study was designed that includes 83 patients (83 eyes) with T2DM but without DR. Three groups were defined based on vitamin D levels, including vitamin D deficiency (serum vitamin D < 20 ng/mL), vitamin D insufficiency (20 ng/mL ≤ serum vitamin D < 30 ng/mL), and normal vitamin D (≥ 30 ng/mL) groups. All patients underwent OCTA with a 6 × 6‐mm scan centered on the fovea. Assessment was conducted on the perfusion density (PD) of the retinal full layer (FL) and the superficial capillary plexus (SCP). In addition, evaluation of the foveal avascular zone (FAZ) included its area, perimeter, and acircularity index (AI).

The PD of the SCP was significantly lower in the vitamin D deficiency group, especially in the temporal regions (42.04 ± 3.8 vs. 44.94 ± 4.5 vs. 47.24 ± 3.9, p < 0.001). The PD of the retinal FL was also significantly lower in the vitamin D deficiency group perifoveal area (32.94 ± 4.5 vs. 35.75 ± 4.2 vs. 35.57 ± 4.4, p < 0.05).

Changes in PD were found to be particularly sensitive to changes in the temporal‐perifoveal region in individuals with vitamin D deficiency. Thus, vitamin D deficiency may be associated with DR.