Poor glycemic control is associated with neuroretinal dysfunction in short-wavelength colour pathways in adolescents with type 1 diabetes

Purpose: Poor glycemic control is a strong risk factor for diabetic retinopathy (DR). The purpose of this study is to identify if neuroretinal changes in short-wavelength colour pathways are potential biomarkers for DR in adolescents with type 1 diabetes and no ophthalmoscopic evidence of DR. Methods: Short-wavelength electroretinograms (sERGs) targeting short-wavelength colour pathways were recorded using blue flashes (peak 410nm) against an amber (594nm) background in 21 patients with type 1 diabetes (16 ± 1.78 years) and 19 controls (17 ± 3.84 years). The outcome measures were implicit time of the b-wave and the amplitude of the photopic negative response (PhNR). These measures represent inner and middle retinal responses respectively. Hemoglobin A1c (HbA1c) values, a measure of long-term glycemic control, were collected closest to the time of testing. Multiple linear regression analyses were conducted to assess the association of HbA1c with each sERG outcome measure while controlling for duration of diabetes. Results: sERG b-wave implicit times were significantly delayed (p=0.0015) and PhNR amplitudes were reduced (p=0.0021) in patients with type 1 diabetes when compared with controls. A multiple regression analysis with PhNR amplitudes in the patient group resulted in a significant association with HbA1c (r=0.57, p=0.004). sERG b-wave implicit times were not associated with HbA1c. Conclusion: Poor glycemic control is associated with neuroretinal dysfunction in short-wavelength colour pathways in adolescents with type 1 diabetes. This dysfunction was found in the inner retina specifically. Inner retinal function in short-wavelength colour pathways may be a potential biomarker for DR progression.