ACE2 and infection: Also, Based on various research in terms of the significant relationship between the underlying diseases and the severity of the SARS-CoV-2 disease, it has been shown that the highest rate of infection is related to diabetic patients, which is one of the important reasons for the severity of the SARS-CoV-2 in diabetic patients due to the increased expression of ACE2 as a receptor for spike virus, in all tissues, especially lungs [44, 45].