As for the influence on immune response, patients with metabolic diseases such as diabetes and obesity often respond to infection with a proinflammatory patterns rather than a protective pattern, which may lead to increased production of cytokines and ROS in COVID-19 infection, fueling the IFN-IDO-Kyn pathway and ROS-Glycolysis axis [129]. This evidence concerns the gene IDO1 and obesity due to melanocortin 4 receptor deficiency.