Aims: The aim of the present study was to investigate retinal nerve fiber layer (RNFL) thickness in patients with type 2 diabetes mellitus (T2D) using spectral-domain optical coherence tomography and to evaluate the relationship between RNFL thickness and carotid intima media thickness (CIMT).
Methods: This study included 171 patients with T2D (53.2 ± 8.8 years) and age matched 61 healthy controls (51.9 ± 8.1 years). We evaluated anthropometric and metabolic parameters as well as RNFL and CIMT measurements in patients with T2D and controls. The Mann-Whitney U test was used to compare the continuous variables and the Chi-square test was used to compare categorical variables. Spearman's rank correlation test was used for calculation of associations between variables.
Results: The average RNFL thickness was 84.82 ± 11.22 μm in patients with T2D and 92.35 ± 8.45 μm in healthy controls (p<0.001). Mean CIMT values were higher in patients with T2D (0.80 ± 0.1mm) than the healthy subjects (0.72 ± 0.1mm) (p<0.001). A significant negative correlation was found between age and all quadrants of RNFL. There was a negative correlation between average RNFL thickness and HbA1c (r=-0.176), uric acid (r=-0.145), CIMT (r=-0.190) and presence of carotid plaque (r=-0.193). The superior RNFL thickness was negatively associated with HbA1c (r=-0.175), CIMT (r=-0.207) and carotid plaque (r=-0.176). There was also an inverse correlation between the inferior RNFL thickness and HbA1c (r=-0.187) and carotid plaque (r=-0.157).
Conclusion: Thinning of RNFL might be associated with atherosclerosis in patients with T2D.
Keywords: Carotid intima media thickness; Retinal nerve fiber layer thickness; Type 2 diabetes.
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