Structural and metabolic retinal markers of mild cognitive impairment in type 2 diabetes

Abstract

Purpose : Non-invasive retinal parameters may be valuable to detect risk of mild cognitive impairment (MCI) in people with type 2 diabetes (T2DM). Therefore, we aimed to investigate whether there is a difference in structural and metabolic retinal markers in people with T2DM with and without MCI.

Methods : We performed a prospective cross-sectional study. individuals with T2DM registered in the Funen Diabetes Database were invited to participate in this study between 25 November 2020 and 25 February 2022. Based on screening with the Montreal Cognitive Assessment (MoCA) scores, a targeted neuropsychological test battery (NTB) was performed to detect MCI in those suspected of cognitive dysfunction. The NTB was comprised of 13 tests covering five cognitive domains; processing speed, attention and executive functioning, memory, visio-construction and language. We performed clinical and ophthalmologic examination including blood pressure, blood samples, best corrected visual acuity measurement (BCVA) and retinal imaging, including 7-field color fundus photos, optical coherence tomography (OCT), OCT-Angiography and retinal oximetry, were performed on all participants. Diabetic retinopathy was graded according to the International Clinical Diabetic Retinopathy severity scale.

Results : We included 134 persons with T2DM. The prevalence of MCI was 28%. Age, gender and diabetes duration did not vary between those with or without MCI but individuals with MCI had completed fewer years of education and were more often taking glucose lowering treatment excl. insulin. There was no difference between presence of any overt DR between groups but individuals with MCI had worse BCVA (84.0 vs 84.5 ETDRS letters p=0.035). In a multivariable cluster analysis adjusting for age, sex and presence of diabetic retinopathy, persons with MCI had significant thinner macular retinal nerve fiber layer (22.3µm vs. 24.1µm, p=0.01) and macular ganglion cell layer (45.7µm vs. 48.4µm, p=0.03), and less venular oxygen saturation in the nasal quadrant (56.3 vs. 61.0, p=0.02) compared to those without MCI. There were no differences in retinal vessel density, fractal dimension, width, tortuosity or OCT-A markers.

Conclusions : People with T2DM and MCI demonstrate alterations in retinal structure and metabolism, suggesting non-invasive retinal markers may be useful to detect those at risk of cognitive dysfunction in people with T2DM.

This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.