COVID-19 often triggers a strong inflammatory response, which leads to significant changes in immune system cell counts. In this study, we analyzed the following blood biomarkers from COVID-19 patients: white blood cells (WBC), monocytes, neutrophils, lymphocytes, eosinophils, C-reactive protein (CRP), basophils, and blood sugar levels (glycemia). We examined various comparisons, correlations, and ratios among these markers to better understand the relationship between pre-existing health conditions and changes in blood markers, as well as how these factors relate to disease severity. Elevated levels of WBC, neutrophils, CRP, and glycemia were observed in more than 60–70% of the patients, with significantly higher glycemia levels found in diabetic patients (P < 0.05). A strong correlation was observed between WBC and neutrophils, which make up the majority of WBCs, and a moderate correlation between monocytes and lymphocytes. Patients with pre-existing conditions generally showed lower levels of lymphocytes, monocytes, and basophils. In particular, diabetic patients had significantly lower lymphocyte and monocyte counts (P < 0.05). The mean and median values of all these hematological parameters were calculated for each group based on their pre-existing conditions.
