Clinical Report: Electroretinography Reveals Functional Deficits in Diabetic Retinopathy
Overview
A 46-year-old male with type 2 diabetes demonstrated progressive diabetic retinopathy (DR) despite systemic glycemic control. Electroretinography (ERG) revealed severely delayed implicit times and reduced amplitudes, correlating with worsening retinal pathology and a high risk of intervention within three years.
Background
Diabetic retinopathy is a common microvascular complication of diabetes that can lead to vision loss. Early detection and monitoring are critical to prevent progression to severe stages and macular edema. Electroretinography provides an objective measure of retinal function, supplementing clinical examination findings. Recent concerns have emerged regarding glucagon-like peptide-1 (GLP-1) agonists potentially exacerbating DR complications.
Data Highlights
| Parameter | Right Eye (OD) | Left Eye (OS) |
|---|---|---|
| Cup-to-disk ratio | 0.45 | 0.55 |
| HbA1c at diagnosis | 6.5% | |
| HbA1c after stopping metformin | 12% | |
| HbA1c after GLP-1 agonist | 6% | |
| ERG DR score | 27.6 (normal <23.5) | |
| ERG findings | Severely delayed implicit time, severely reduced amplitude OU | |
Key Findings
- Initial retinal exam showed blot hemorrhage and cotton-wool spot OD; OS was initially unaffected.
- Patient diagnosed with type 2 diabetes after initial visit; HbA1c initially 6.5%.
- Worsening DR bilaterally with increased hemorrhages and cotton-wool spots over time despite glycemic control.
- Discontinuation of metformin led to HbA1c spike to 12%, followed by improvement with GLP-1 agonist therapy.
- ERG revealed severely delayed implicit times and reduced amplitudes with a DR score of 27.6, indicating an 11-fold increased risk of intervention within 3 years.
- GLP-1 agonists may contribute to DR complications; ongoing trials are investigating their long-term retinal effects.
Clinical Implications
Electroretinography can objectively detect functional retinal impairment in diabetic retinopathy, even when patients report stable vision. Clinicians should closely monitor patients initiating or using GLP-1 agonists for potential worsening of DR. Early referral to retina specialists is warranted when ERG and clinical findings indicate progression or risk of macular edema.
Conclusion
This case highlights the utility of ERG in detecting functional retinal changes in diabetic retinopathy and underscores the need for vigilant monitoring of patients on GLP-1 agonists. Integrating functional testing with clinical examination can guide timely intervention to prevent vision loss.
References
- Marso SP et al. 2016 -- Semaglutide and cardiovascular outcomes in patients with type 2 diabetes
- Singh H et al. 2025 -- Association between glucagon-like peptide-1 agonists and risk of diabetic retinopathy
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