ABSTRACT
Diabetes mellitus (DM) is a metabolic disease characterised mainly by signs and symptoms derived from increased serum glucose or hyperglycemia. The coronavirus disease 2019 (COVID-19) pandemic affected the entire world with reports of severe prognosis in diabetic patients infected with the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and high hospital admissions in the intensive care unit (ICU) compared to non-diabetic patients. The objective of the bibliographic review was to evaluate and describe some of the biochemical mechanisms that lead to severe prognosis in patients with DM infected by the SARS-CoV-2 virus through a systematic search for information in different databases. The results showed that the high ICU admission with a severe prognosis of diabetic patients infected by the virus was due to excessive inflammation that causes acute respiratory distress syndrome, cytokine storm, severe pneu-monia, impaired immunity, and hyperglycemia. The virus enters the cell mainly through the endocytic and non-endosomal pathway;the central cellular receptors involved in the mechanisms are insulin receptors (IR), glucose transporter type 2 (GLUT-2), dipeptidyl peptidase-4 (DPP4), glucose transporter type 4 (GLUT-4), glucose converting enzyme angiotensin 2 (ACE2), and the serine transmembrane protease co-receptor 2 (TMPRSS2) essential for viral propagation. The increased susceptibility to devel-oping COVID-19 in diabetic patients is due to the overexpression of ACE2, and serious complications are increased at the microvascular and macrovascular levels, such as nephropathies, neuropathies, and cardiovascular diseases.