Role of comorbidities like diabetes on severe acute respiratory syndrome coronavirus-2: A review

Pandemic coronavirus disease-2019, commonly known as COVID-19 caused by severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) is a highly contagious disease with a high mortality rate. Various comorbidities and their associated symptoms accompany SARS-CoV-2 infection. Among the various comorbidities like hypertension, cardiovascular disease and chronic obstructive pulmonary disease, diabetes considered as one of the critical comorbidity, which could affect the survival of infected patients. The severity of COVID-19 disease intensifies in patients with elevated glucose level probably via amplified pro-inflammatory cytokine response, poor innate immunity and down-regulated angiotensin-converting enzyme 2. Thus, the use of ACE inhibitors or angiotensin receptor blockers could worsen the glucose level in patients suffering from novel coronavirus infection. It also observed that the direct beta-cell damage caused by virus, hypokalemia and cytokine and fetuin-A mediated increase in insulin resistance could also deteriorate the diabetic condition in COVID-19 patients. This review highlights the current scenario of coronavirus disease in pre-existing diabetic patients, epidemiology, molecular perception, investigations, treatment and management of COVID-19 disease in patients with preexisting diabetes. Along with this, we have also discussed unexplored therapies and future perspectives for coronavirus infection.