Platelet-to-Neutrophil Ratio Emerges as Key Diagnostic Marker for Diabetic Macular Edema: Study Finds

"A PNR of ≤68.51 showed a strong association with diabetic macular edema in patients with diabetic retinopathy, regardless of optical coherence tomography (OCT) morphological patterns. This suggests that PNR could serve as a useful diagnostic marker, aiding early detection and improving risk assessment and management in DR," the researchers reported in BMC Ophthalmology.

The platelet-to-neutrophil ratio, a novel biomarker combining platelet and neutrophil counts, offers a comprehensive reflection of thrombotic and inflammatory activity and their interaction. While it has shown predictive value in conditions such as acute ischemic stroke, hemorrhagic transformation, and Graves' orbitopathy, its application in ophthalmology remains limited.

Recognizing this gap, Xiyuan Zhou, Department of Ophthalmology, The Second Affiliated Hospital of Chongqing Medical University, Chongqing, China, and colleagues aimed to evaluate the diagnostic potential of PNR in detecting diabetic macular edema among patients with diabetic retinopathy, potentially offering a new tool for early identification and improved clinical management.

For this purpose, the researchers conducted a cross-sectional study involving 366 participants divided into four groups, including patients with DME, DR without DME, diabetes without DR, and healthy controls. They calculated the platelet-to-neutrophil ratio and assessed its association with DME presence and subtypes, as classified by OCT features. Using multivariate logistic regression and ROC curve analysis, they evaluated PNR’s potential as a predictive marker for DME.

The following were the key findings of the study:

• The DME group showed significantly lower PNR levels [median: 50.73] compared to the DR [95.63], DM [92.39], and healthy control groups [100.66].
• There were no significant differences in PNR levels among different DME subtypes based on OCT features.
• ROC curve analysis showed that PNR is a strong predictor of DME, with an AUC of 0.832.
• A PNR cut-off value of 68.51 yielded 80.2% sensitivity and 75.6% specificity for predicting DME.
• Multivariate regression analysis identified PNR ≤ 68.51 as an independent risk factor for DME in DR patients (OR = 12.05).

The authors highlighted that diabetic retinopathy patients with lower platelet-to-neutrophil ratio levels are more likely to develop diabetic macular edema (DME), with further analysis identifying a threshold value of ≤68.51 as strongly associated with DME onset. They noted that PNR could serve as a promising diagnostic marker, potentially enhancing risk stratification and guiding management in DR patients.

However, they emphasized the need for further studies to better understand the relationship between PNR and DME development and to validate its clinical applicability across wider populations.

Reference:

Sun, H., Li, Y., Liu, S. et al. The diagnostic value of platelet-to-neutrophil ratio in diabetic macular edema. BMC Ophthalmol 25, 167 (2025). https://doi.org/10.1186/s12886-025-04001-2