Objectives: To study the clinical profile and outcome of critically ill nCOVID-19 Patients with special reference to Diabetes Mellitus and to compare and contrast the clinical course, Inflammatory markers, and outcome of critically ill Covid 19 patients with and without Diabetes Mellitus. Study Design: Prospective Observational Study. Study Setting: This study was conducted at SSG Hospital, a tertiary care hospital in Vadodara. Participants: 150 patients in the age group between 18 -80 years and having SpO2 < 90% on room air or respiratory rate of more than e >24 were included in the study. Results: The presence of underlying diabetes in patients with COVID-19 is associated with an increased risk of mortality as well as the severity of COVID-19. This study also suggests that there is an increase in mortality in diabetic patients aged more than 45. In patients who had uncontrolled diabetes COVID-19, the disease severity was greater than in patients who had controlled diabetics. Amongst patients having severe COVID-19 uncontrolled diabetics had significantly higher mortality than controlled diabetes. No such significant difference was found in mortality amongst moderate COVID-19 patients having either controlled or uncontrolled diabetics. Higher mean scores (≥3) of inflammatory markers on admission were associated with diabetics.