Biochemical Biomarkers Can Offer Insight Into Diabetic Retinopathy Stage

Biochemical biomarkers including serum urea, diffuse retinal thickness (DRT), and the epiretinal membrane (ERM) may serve as imaging biomarkers for advanced diabetic retinopathy (DR), according to research published in Clinical Ophthalmology.

Researchers sought to compare imaging and biochemical biomarkers in patients with type 2 diabetes mellitus and diabetic macular edema (DME) at various stages of DR. Between May 1, 2020 and October 31, 2021, the research team conducted a cross-sectional, observational study of 100 eyes from 100 patients (mean age, 54.84±9.87 years; 76% men) with type 2 diabetes mellitus with DR and DME. 

Patients were separated into 2 study groups: group A, DME with nonproliferative diabetic retinopathy (NPDR), and group B, DME with proliferative diabetic retinopathy (PDR). Group A was further separated into 3 categories: group A1, DME with mild NPDR, group A2, DME with moderate NPDR, and group A3, DME with severe NPDR. In total, group A1 had 1 patient, group A2 had 44 patients, group A3 had 29 patients and group B had 29 patients. Since group A1 had only 1 patient, researchers did not include it in the calculation. The average duration of diabetes in group A was 10.59±5.21 years, and the average duration of diabetes in group B was 9.82±5.72 years, 

According to the report, the HbA1c levels, serum triglyceride level, serum cholesterol level, and microalbuminuria level showed no significant associations with various stages of DR (P >.05). The researchers found high serum urea levels (P =.027) in group B patients. 

Optical coherence tomography (OCT)-based imaging biomarkers such as central subfield thickness (CST), cystoid macular edema (CME), subretinal fluid (SRF), and hyperreflective foci (HRF) showed no significant association with different stages of DR, the team noted. They found that the presence of DRT (P =.04) and the ERM (P =.04) showed a significant association in group B patients.

“Imaging biomarkers such as patterns of OCT findings, those being DRT and ERM have the potential to be the indicators for assessing the severity of the disease, but significant conclusions could not be drawn due to the lack of sufficient sample,” the researchers explain. “Likewise, biochemical biomarkers such as serum urea and microalbuminuria were found to be deranged in severe stages of the disease, which needs further evaluation to be concluded as indicators of disease severity.”

Limitations of the research include the inadequate sample size and an overrepresentation of men in the study cohort.