Background: Poor glycemic management has been linked to increased mortality from previous viral pandemics, including H1N1 flu and SARS. Incorporating diabetes status assessment into risk management for COVID-19 pneumonia patients is currently proposed by many investigations. Objective: Assessment of the impact of uncontrolled diabetes on the course of COVID-19 pneumonia in critically ill patients by measuring glycosylated hemoglobin (HbA1c) in the first 48 hours of admission. Methods: A retrospective cohort study was conducted on 40 critically ill patients from October 2021 to April 2022; recruiting patients admitted to the critical care department in Beni-Suef university hospital. HbA1c was measured in the first 48 hours from admission. Results: This study was conducted on 40 patients. Fifty per cent of the participants had diabetes, and 62.5% were hypertensive. There was a significant association between the higher HbA1c level (more than8.7%) and the need for mechanical ventilation (MV), higher length of stay in intensive care unit (ICU) and mortality in diabetic patients. The HbA1c had a statistically significant role in predicting the need for MV in diabetics. At a cut-off of 8.7%, HbA1c can predict the need for MV with 91% sensitivity and 63% specificity in diabetic patients. Likewise, the HbA1c had a statistically significant role in predicting mortality in the diabetic group. At a cut-off of 8.5%, HbA1c can predict mortality with 90.9% sensitivity and 89% specificity in diabetic patients. Conclusions:  High  HbA1c led to increasing sepsis parameters , the need for mechanical ventilation , hospital stay and  the mortality in diabetic patients with COVID-19 pneumonia.