After the emergence of the novel 2019 coronavirus disease in P. R. China, this highly contagious disease has been currently spread out to almost all countries, worldwide. Novel 2019 coronavirus disease, Middle East respiratory syndrome, and severe acute respiratory syndrome are reported to cause a higher risk for severe infections in patients with chronic comorbidities, such as hypertension and diabetes. These severe infections can contribute to higher rates of morbidity and mortality in these patients. In the present review, we discussed the role and underlying mechanisms of the two most common chronic diseases, type-2 diabetes mellitus and hypertension, in clinical manifestations and disease severity of novel 2019 coronavirus disease, Middle East respiratory syndrome and severe acute respiratory syndrome, with the hope to provide evidence for better decision-making in the treatment of this vulnerable population.