Prevalence of COVID-19 Among Older People with Type 2 Diabetes Mellitus: A Systematic Review

Abstract

Background: On March 11, 2020, the WHO proclaimed the Coronavirus Disease 2019 (COVID-19) pandemic owing to coronavirus-2 (SARS-CoV-2). SARS-CoV-2 is a zoonotic virus that may be spread from bats to humans through airborne droplets and aerosols. SARS-CoV-2 spike protein has a high binding affinity for ACE2 receptors, widely expressed throughout the respiratory system, notably in epithelial lung cells. ACE2 receptors are found in intestinal mucosal, endothelial, heart, renal epithelial as well as cerebral neuronal cells, explaining COVID-19 extrapulmonary symptoms like diarrhea, nausea, vomiting, chest pain, heart failure, renal injury, headache, and confusion. Older persons with type2 diabetes mellitus and hypertension are more susceptible to SARS-CoV-2 infection as drugs by which they are treated promote ACE2 receptor expression. Moreover, comorbidities increase the probability of poor outcomes after infection by the SARS-CoV-2. Research links COVID-19 to hyperglycemia in the elderly with type 2 diabetes. Twenty percent of people with diabetes get severe pneumonia and a septic course from viral infections. Diabetes contributed to sickness severity and fatality in MERS (MERS-CoV). Epidemiological findings in SARS-CoV-2-affected regions, CDC data, and other national health centers and hospitals suggest that individuals with diabetes had a 50% greater chance of dying from COVID-19. Methods: This systematic review involves a critical and reproducible summary of the results of the available publications on COVID-19 and diabetic elderly patients’ topics and questions. Fourteen studies (6 retrospective cohorts, two prospective, two cohorts, one combined retrospective, one observational, one cross-sectional, and one hospital-based study) were included in this systematic review. Results: From all studies, the mean age of older adults with type 2 diabetes mellitus who suffered from COVID-19 was 50 to 89 years. The majority of the studies showed the male predominance of infection. The pooled prevalence of COVID-19 among diabetes mellitus elderly patients was 29.8%. Conclusions: Diabetes patients had a greater COVID-19 prevalence and severity, according to several explanations. Diabetes Mellitus increases the risk of infection due to innate and adaptive immunity deficiencies. Post COVID-19 complications arise due to a lack of equilibrium between pro-inflammatory and anti-inflammatory cytokine networks in type 2 diabetes mellitus, contributing to increased mortality. Therefore, this study necessitates a large investigational study to find out how to boost the immune response against SARS-CoV-2 infection in an equilibrium manner not to produce much inflammatory cytokine in type 2 diabetes mellitus individuals to reduce the risk of developing complications and mortality consequently. Keywords: COVID-19, Diabetes mellitus, Type-2 diabetes, Elderly.