The longitudinal relationship between carotid arterial disease and retinopathy complicating type 2 diabetes: The...

To investigate whether i) ultrasonographically-assessed carotid arterial disease (CAD) is associated with diabetic retinopathy (DR) progression and retinal microangiopathy measured by optical coherence tomography angiography (OCTA), and ii) baseline DR prevalence and/or OCTA parameters are associated with CAD progression in type 2 diabetes.

Participants in the Fremantle Diabetes Study Phase II (n = 164, mean age 69.7 years, 55.5% males) in whom carotid ultrasonography/OCTA was performed in 2018-2019 were restudied a mean 3.7 years later. Generalized estimating equations assessed associations between baseline CAD indices and new/worsening DR and OCTA parameter changes, and between baseline DR status/OCTA parameters and changes in CAD metrics.

Carotid stenosis (focal wall thickening ≥50% or intima-media thickness (IMT) > 1.5 mm) and carotid bifurcation IMT ≥1 mm at baseline were independently associated with reductions in superficial capillary plexus parafoveal vessel density (regression coefficients (95% CI) 0.73 (0.02 to 1.43) and 0.88 (95% CI: 0.06 to 1.69); P = 0.043 and 0.035, respectively). There were no independent associations between CAD parameters and new/worsening DR. There were no significant associations between baseline DR/OCTA parameters and new/worsening carotid stenosis.

CAD may contribute to early DR in type 2 diabetes but we found no evidence of a bidirectional relationship.