Fetuin-A levels in diabetic retinopathy: a systematic review and meta-analysis

Diabetic retinopathy (DR) is one of the main microvascular complications of diabetes and one of the most common causes of vision loss worldwide. Fetuin-A is a glycoprotein correlated with insulin resistance and has been measured in DR patients. Herein, we aimed to investigate these studies through a systematic review and meta-analysis.

Four online databases, including PubMed, Embase, Scopus, and the Web of Science were searched comprehensively in order to retrieve relevant studies that compared blood fetuin-A levels in patients with DR vs. non-DR, DR vs. non-diabetic controls, non-DR vs. non-diabetic controls, and proliferative vs. non- proliferative DR. Random-effect meta-analysis was performed for the calculation of the standardized mean difference (SMD) and 95% confidence interval (CI).

From the 186 found results through database search, after eligibility assessment, seven studies were included. A total of 1104 cases with a mean age of 57.24 ± 9.62 years were investigated. Meta-analysis showed that fetuin-A levels were significantly higher in patients with DR compared to both non-DR diabetic patients (SMD 0.41, 95% CI 0.10 to 0.72, P = 0.009), and non-diabetic healthy controls (SMD 0.77, 95% CI 0.47 to 1.07, P < 0.0001). Additionally, patients with proliferative DR had higher fetuin-A levels than those with non-proliferative DR (SMD 0.35, 95% CI 0.11 to 0.59, P = 0.004). However, no significant difference was found between diabetic patients without DR and healthy controls.

Based on our findings, fetuin-A was higher in patients with DR and could be potentially used for measurement in clinical settings if confirmed in future large-scale studies. Moreover, the fact that higher fetuin-A levels were associated with proliferative DR could have clinical implications.