A new study published in Frontiers in Endocrinology, led by a team of Chinese researchers, evaluated the clinical utility of peripheral complete blood count as a biomarker for diabetic macular edema (DME).
Give me some background first.
Multiple studies have shown that chronic retinal inflammation plays a critical role in the pathogenesis of DME.
As white blood cell (WBC) count is an effective biomarker for inflammation, this study sought to better understand the relationship between peripheral blood biomarkers and DME pathogenesis.
Now talk about the study.
In this hospital-based, cross-sectional study, investigators measured the central macular thickness (CMT) of diabetic patients—with DME characterized as CMT >300 μm—and compared these results to complete blood count tests.
Patient criteria?
The study authors included the contralateral eyes of patients with type 2 diabetes who had undergone vitrectomy for proliferative diabetic retinopathy (PDR).
In total, 239 PDR patients were enrolled, with an average age of 55 and a mean CMT of 284.23 μm.
Findings?
Investigators found a significantly negative association between CMT and both WBC count (95% confidence interval [CI] -22.08, p= 0.0218) and neutrophil count (95% CI -28.02, p=0.0259).
Go on…
An inverse relationship between DME and multiple WBC subtypes was observed, including:
- WBC count (odds ratio [OR] 0.75, 95% CI 0.59, p=0.0153)
- Monocyte count (OR 0.07, 95% CI 0.00, p=0.0431)
- Eosinophil count (OR 0.75, 95% CI 0.00, p=0.0420)
Expert opinion?
According to the study authors, as PDR is characterized by neovascularization and proliferative membrane formation, “WBCs may enter the retina through the compromised blood-retina barrier.”
“Compared to patients without DME, PDR patients with DME have more severe damage to the blood-retina barrier, which may lead to an increase in WBCs in the bloodstream entering the eye, leading to a decrease in WBCs and all subtypes in circulation,” they stated.
Take home.
Lower physiological peripheral WBC levels were associated with increased CMT and incidence of DME in Chinese PDR patients.
Additionally, DME was correlated with low monocyte and eosinophil counts.
While further studies are necessary to discern the association between WBC subtypes and DME, this study shows the value of using peripheral complete blood count—an affordable and accessible test—to evaluate this relationship.