Coronavirus disease 2019 (COVID-19) is a global pandemic where several comorbidities have been shown to have a significant effect on mortality . Patients with diabetes mellitus (DM) have a higher mortality rate than non-DM patients if they get COVID-19 . Recent studies have indicated that patients with a history of diabetes can increase the risk of severe acute respiratory syndrome coronavirus 2 infection . Additionally, patients without any history of diabetes can acquire new-onset DM when infected with COVID-19 . Thus, there is a need to explore the bidirectional link between these two conditions, confirming the vicious loop between``DM/COVID-19". This narrative review presents (1) the bidirectional association between the DM and COVID-19, (2) the manifestations of the DM/COVID-19 loop leading to cardiovascular disease, (3) an understanding of primary and secondary factors that influence mortality due to the DM/COVID-19 loop, (4) the role of vitamin-D in DM patients during COVID-19, and finally, (5) the monitoring tools for tracking atherosclerosis burden in DM patients during COVID-19 and``COVID-triggered DM"patients . We conclude that the bidirectional nature of DM/COVID-19 causes acceleration towards cardiovascular events . Due to this alarming condition, early monitoring of atherosclerotic burden is required in `` Diabetes patients during COVID-19"or``new-onset Diabetes triggered by COVID-19 in Non-Diabetes patients".