A systematic review approach in understanding the COVID-19 mechanism in diabetes and its progression to diabetic microvascular complications

Abstract

Introduction: In uncontrolled hyperglycemia, lungs, tongue, oropharyngeal and nasopharyngeal airways having increased glycosylated angiotensin-converting enzyme 2 (ACE2) can serve as good viral binding sites for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) leading to a greater tendency and considerable risk of prolonged life-threatening disease. This review was written with the objective to extract the recent advances, updates, and discoveries about the effects of coronavirus disease-2019 (COVID-19) on patients with diabetes and its microvascular complications. It was further written with the aim to discuss the current state of knowledge that has not yet been confirmed or unconfirmed, leading to various debatable issues about COVID-19-associated with microvascular complications in diabetes mellitus. Materials and Methods: We followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines and searched scientific sites related to our review article such as Web of Science, Embase, PubMed, Scopus, Google Scholar, and MEDLINE of last nearly two and half years. Results: The individuals who are suffering from type 2 diabetes mellitus experience more organ damage by SARS-Cov-2 due to cytokine storm. The pro-inflammatory state, lower primary immune system response, and increased ACE2 level with dysregulation of vascular function and the prothrombic state in patients with diabetes may increase the vulnerability for COVID-19 and worsened prognosis. The patients have reduced prognosis leading to microvascular complications such as diabetic nephropathy, neuropathy and retinopathy. In diabetes retinopathy, it induces the changes in the vasculature of the retinal veins. These viruses can directly affect the nervous tissue and/or can indirectly via activating the immune system-mediated mechanisms leading to diabetic neuropathy as well. Conclusions and Implications: During the cytokine storm the amount of D-dimer in the serum gets significantly increased, due to increased activating plasmin at the early stage of inflammation. Uncontrolled hyperglycemia leads to diabetic complications leading to increased mortality rate in patients with COVID-19. Thus, diabetes and its associated microvascular complications may lead to the severity and mortality in the patients with COVID-19. More of clinical practice and further studies should be implicated through this review article. Laboratory findings and clinical records are of much help in patients with diabetes and COVID-19. Worldwide studies from different countries apart from China should be considered to reach a conclusion about the conditions of patients with diabetes and microvasculature complications around the world.