Management of COVID-19 patients with underlying disorders is a challenging issue at any time. The present survey investigated the mortality rate of COVID-19 patients with various underlying disorders. Our data revealed that the mortality rate in patients with both DM and HTN is higher. Diabetes mellitus, through the reduction of neutrophil chemotaxis and the disruption of monocyte activity and phagocytosis, leads to immune system suppression. The interaction of SARS-CoV-2 and lung cells is mediated by angiotensin-converting enzyme (ACE) 2, which is highly expressed in the lungs and cardiovascular systems. SARS-CoV-2 infection of monocytes plays a role in COVID-19 pathogenesis by initiating cytokine storms, with infected monocytes expressing more ACE2, the receptor for SARS-CoV-2. In COVID-19, monocyte activation upregulates Hypoxia-inducible factor-1-α (HIF-1α), which is induced in hypoxia, leading to increased glycolysis (
19,
20). SARS-CoV-2 replication is fueled by adenosine triphosphate (ATP) and pyruvate produced in the glycolysis pathway, especially in diabetic patients (
21). In type I DM, elevated glucose levels during COVID-19 infection alter insulin needs, accompanied by increased pro-inflammatory cytokines, such as interleukin-1β (
22). Additionally, glucose increases monocyte function and virus replication in a dose-dependent manner, worsening COVID-19 in diabetic patients (
21,
23).
The present study showed that the mortality rate is significantly higher in patients with both DM and HTN compared to those with DM, HTN, and CVD. The exact mechanisms through which HTN affects COVID-19 pathogenesis are not well understood, but several pathways have been reported. Hypertension exacerbates COVID-19 progression by influencing endovascular system inflammation and anti-inflammatory responses. By causing vessel stiffness, increasing inflammatory cytokines (e.g., IL-1β), and promoting oxidative stress, HTN worsens COVID-19 pathogenesis (
24). Conversely, increased T regulatory cells and anti-inflammatory cytokine secretion reduce SARS-CoV-2 clearance (
25).
There are disagreements regarding the role of Angiotensin II (Ang II) and Ang II receptor blockers in COVID-19. Some studies have suggested that Ang II receptor blockers, used for treating HTN, increase ACE2 expression, potentially heightening susceptibility to COVID-19 infection (
26). However, it has also been shown that Ang II blockers may reduce inflammation caused by HTN in COVID-19 patients (
27,
28). A recent study found that using renin-angiotensin-aldosterone system (RAAS) inhibitors does not increase the risk of COVID-19 infection (
29). In contrast, Ang II may enhance B-cell and plasma cell activity, worsening COVID-19 (
27).
A comprehensive investigation in Italy showed that HTN was more common in hospitalized COVID-19 patients. However, a considerable number of discharged patients had negative risk factors such as DM, HTN, COPD, kidney failure, and older age (
30). These findings suggest that HTN is an independent factor in COVID-19 development (
31). Hypertension has also been associated with reduced antibody production after vaccination (
16-
18), leading to increased vulnerability to COVID-19 due to lower immunity. Chronic kidney disease, lung disease, COPD, DM, and immunocompromising conditions reduce vaccine effectiveness, causing breakthrough infections and increased hospitalization risk (
32). A recent study confirmed that HTN, DM, and older age significantly increase the mortality rate of COVID-19 (
33).
We observed that patients with DM had lower WBC counts, which were significantly higher in deceased patients. A significant borderline difference in lymphocyte count was noted, likely due to sample size. The number and type of underlying disorders influence the immune response and lymphocyte production (
34). C-type lectin receptors (CLRs) are key in regulating the immune response. These receptors recognize pathogenic antigens by their glycans, initiating an inflammatory response (
35). In diabetic patients, high glucose levels activate CLRs, triggering inflammatory pathways and cytokines, which contribute to cytokine storms in COVID-19 (
36). This explains our finding that glucose levels were significantly higher in deceased patients.
A nationwide study in India, involving 40,691,059 COVID-19 patients, identified mortality risk factors over 25 months, revealing a 0.7% mortality rate and 8.5% hospitalization rate. The study found that DM, HTN, older age, and CVD significantly increased the COVID-19 mortality rate (
37). A similar nationwide investigation by Isath et al. found that the mortality rate (13.6%) was significantly higher in ventilated COVID-19 patients, with socioeconomic and racial disparities impacting survival (
38). The frequency of major adverse cardiovascular events was notably higher in COVID-19 patients aged 18 - 39 (
39), supporting our findings that comorbidities worsen prognosis. Myocardial injury during COVID-19 was more common in men, aligning with our finding that the mortality rate was higher in males (
40).
5.1. Limitations
The main limitation of the present survey is the lack of data on the survival of patients without comorbidities. Additionally, investigating the effect of comorbidities on COVID-19 patients following vaccination could provide valuable insights. Treatment strategies for comorbidities may vary across countries, influencing outcomes. This study did not account for treatment strategies, which may have confounded the results.
5.2. Conclusions
In this study, after evaluating 500 patients with comorbidities, we observed a 15% mortality rate. Our findings indicate that a history of HTN and DM are important risk factors for the outcome and survival of COVID-19 patients. Lower WBC counts, neutrophilia, higher BUN, Cr, and AST levels were associated with survival outcomes. Therefore, more attention is required for COVID-19 patients with HTN and DM. Given the discrepancies with recent investigations, further studies with longer follow-up are recommended.