With regard to worse outcome and higher mortality of COVID-19 in older patients with diabetes mellitus or cardiovascular disorders, PDE4 inhibitors possess an advantage as they are able to increase a PDE4 activity in elderly, to reduce a body weight, to improve an insulin sensitivity [219], and to prevent adverse cardiovascular events of nonselective PDE inhibitors (xanthines) [220]. The gene discussed is PDE4A; the disease is COVID-19.