: COVID-19 is a major emerging disease that affects any certain condition. However, a recent report suggests the occurrence of hyperglycemia without any present diabetes in COVID-19 patients. This study aimed to systematically review recent evidence on hyperglycemia in COVID-19 patients. Literature research was done using four search engines, consist of Google Scholar, Pubmed, Science Direct, and ProQuest, and limited to English manuscript only and published in the last 1 year. SARS-CoV-2 could damage the pancreas by causing the destruction of the β-cell structure that leads to impairment of glucose metabolism and worsen pre-existing diabetes or determine the appearance of hyperglycemia in non-diabetes. Inflammation also plays a major important role in hyperglycemia related to COVID-19. Hyperglycemia increased the vulnerability of the lung, by promoting and facilitating the entry of the SARS-CoV-2 into the host cells, and decreasing lung function. Moreover, the mortality and morbidity rate conceivable increased due to hyperglycemia. The presence of high glucose levels is linked with the progression of COVID-19 severity. Thus, the glucose level should be concerned, either in a patient with present diabetes or without any presence of diabetes. Examination and monitoring of glucose levels might be a useful tool to prevent the seriousness of COVID-19..