Background: Uncontrolled Type 2 Diabetes Mellitus (T2DM) has been shown to be associated with an increased severity of COVID-19, it represents an important risk factor for adverse outcomes. Altered glucose metabolism was the basis of the viral infection, leading to a fatal inflammatory reaction, The relationship between COVID-19 and diabetes mellitus is complicated and bidirectional.  Diabetes mellitus is considered one of the most important risk factors for a severe course of COVID-19. At the same time, severe COVID-19 infection, and its treatment with steroids, may have negative impact and side effects on diabetes itself, leading to worsening of hyperglycemia through increased insulin resistance and reduced β-cell secretory function.  The aim of the study is to evaluate biochemical abnormalities in infected type 2 diabetic patients comorbid with COVID 19. Methods: The current study is a case control study was conducted on 89 persons, 35 males and 54 females of the same age group (40:75 years) were selected from outpatient clinic of diabetes, Diabetes and Endocrinology unit, and Intensive care unit of Department of internal medicine at Minia University Hospital from December 2021 to May 2022. Results: D-Dimer levels significantly higher in diabetic with COVID-19 group than diabetic group with p value (>0.001). Serum cholesterol levels significantly higher in diabetic with COVID-19 group than diabetic group with p value (0.01). Conclusion, D-dimer is a good prognostic biomarker for outcome of type 2 diabetic patients infected with COVID-19.