Diabetes Mellitus (DM) affects 537 million people worldwide1 and a substantial part of its impact stems from its vascular complications,2 classically classified as macrovascular and microvascular.

CAD is the most prevalent macrovascular complication, between 14 and 21 %, and the most lethal one.3,4 The gold standard method for assessing CAD is coronary angiography, however its costs and risks restrict its routine use. Coronary computed tomography angiography (CCTA) is a non-invasive imaging technique that allows assessment of luminal reductions in coronary arteries, their walls and the characteristics of atherosclerotic plaques.5,6 CCTA has high accuracy compared to coronary angiography and the new information aggregated by this method has allowed a better stratification regarding the risk of acute coronary syndromes.7

DR is the main microvascular complication of DM and the main cause of blindness among adults aged 20 to 74 years.8 7-field color retinography is the initial modality indicated used for its assessment, and fluorescein angiography is the gold-standard modality.9 However, this last method requires intravenous contrast, is time-consuming, provides low-resolution images, and the quantification of findings is difficult. Multimodal retinal imaging (MMRI) revolutionized the diagnostic workup and provided extremely useful new insights into the pathogenesis of retinal diseases.10 Ultra-wide field retinal imaging (UWF) allows high quality and fast fundus image, with visualization of a larger area of the retina, 200°, that is, 80–85 % of the total area of the retina, allowing for better diagnosis of peripheral changes. Spectral domain optical coherence tomography (SD-OCT), optical coherence tomography angiography (OCTA) are more recent techniques.11., 12., 13. They provide, without the use of intravenous contrast and in high resolution, 3-dimensional images of the retinal layers (SD-OCT), microvasculature (OCTA) and choroid. It is possible to detect early microvascular alterations14 and may even improve the staging of the RD, by offering objective and quantitative parameters, such as foveal avascular zone (FAZ) area, FAZ circularity and mean vascular density (MVD).15

Recent clinical studies suggest an association between DR and CAD.16., 17., 18. Among diabetic patients with CAD, those with DR have a higher mortality rate than those without.38 However, these studies used invasive diagnostic methods or which, although feasible at the bedside, no longer express the new diagnostic and pathophysiological knowledge of the two illnesses. Our primary objective was to investigate the association between the presence and severity of obstructive CAD - assessed by CCTA - and DR - assessed by multimodal retinal imaging (MMRI): UWF, OCTA and OCT-SD- in diabetic patients. The secondary objective was to identify clinical, laboratory and angiographic biomarkers independently associated with DR.