# The serum vitamin D status in adults with diabetic retinopathy: A systematic review and meta-analysis

## TL;DR

This study finds that adults with diabetic retinopathy have significantly lower vitamin D levels than normal, suggesting a link between vitamin D deficiency and the condition.

## Contribution

The study provides the first comprehensive meta-analysis of serum vitamin D levels in diabetic retinopathy patients.

## Key findings

- The pooled mean 25(OH)D level in diabetic individuals was 16.04 ng/mL, below the normal range.
- Patients with DR had a 25(OH)D3 level of 10.68 ng/mL, significantly lower than normal.
- 1,25(OH)2D3 levels were also reduced in DR patients, averaging 31.14 pg/mL.

## Abstract

Emerging evidence suggests that vitamin D may play a crucial role in the development of diabetic retinopathy (DR). However, the extent of vitamin D deficiency in individuals with DR remains uncertain. This study aimed to evaluate serum vitamin D levels in adults with DR.

A literature was retrieved using the Embase, PubMed and Cochrane databases to identify observational studies that evaluated the levels of 25(OH)DS, 1,25(OH)2D5 or total 25(OH)D in the serum of patients with DR. A total of 31 independent studies were included for meta-analysis.

The pooled mean concentration of total 25(OH)D among individuals with diabetes was 16.04 ng/mL (95% CI: 15.13-16.96; I2 = 98.8%), while the mean serum level of 25(OH)D3 in those with DR was 10.68 ng/mL (95% CI: 5.94-15.41; I2 = 99.5%), both significantly below the normal reference range. The average concentration of 1,25(OH)2D3 was 31.14 pg/mL (95% CI: 24.35-37.94; I2 = 98.8%).

The evidence from this meta-analysis indicates an association between vitamin D deficiency and an increased risk of DR.