Clinical epidemiological link between type 2 diabetes mellitus and COVID-19

Introduction: : Multiple studies support the association between type 2 diabetes mellitus (DM2) and the severe clinical course of coronavirus disease 2019 (COVID-19). This systematic review was carried out with the aim of determining the clinical-epidemiological link between DM2 and COVID-19. Methods: A systematic review of articles included in the Embase, Web of Science, Cochrane, PubMed, Scielo and Scopus databases (Q1- Q4), published from February 7, 2020 to October 2021, was carried out. To evaluate the study quality, quality assessment tools were used. Results: A total of 32 studies were analyzed, 65.6% were single-center, 87.5% were retrospective studies, in 18.8% studies only patients with COVID-19 and DM2 were included. In 84.3% of the studies, the predominant sex of the patients was male. In 47% of the studies, the age of the patients was greater than or equal to 60 years. In addition, 90.6% of studies reported comorbidities such as hypertension. 87.5% were good quality studies. Conclusions: : The following stand out as points of convergence in the current scenario of the syndemic between COVID-19 and DM2: advanced age, deterioration of the immune response, higher levels of inflammatory markers and the association with complications and comorbidities of DM2. DM2 is considered a high risk factor for critical clinical conditions and deaths from COVID-19. Likewise, possible multifaceted pathological pathways triggered by hyperglycemia that cause considerable vulnerability to SARS-CoV-2 infection have been detailed.