2.3 COVID-19 infection and diabetic nephropathy

COVID-19 patients with comorbidities are more likely to show a more severe clinical picture of the infection with high mortality rate. Most of the available data highlight diabetes mellitus as one exceptional comorbidity associated with more severe COVID-19 and mortality (D’Marco et al., 2020). A survey done in the United Kingdom showed that out of 23,804 patients with COVID-19 dying in hospitals, 1.5% had type 1 diabetes mellitus and 32% had type 2 diabetes mellitus, with 3.5 and 2.03 times the odds of dying compared to patients without diabetes mellitus respectively (Apicella et al., 2020). It has been observed that patients with diabetes mellitus have a severe and fatal manifestation of COVID-19 disease with increased ACE2 production as an adaptive response to elevated levels of angiotensin I and II, which in effect facilitates the entry of SARS-CoV-2 into host cells (Pal and Bhansali, 2020). This phenomenon enhances a progressive decline in renal function in diabetic patients characterized by an increase in serum creatinine, uric acid, BUN, proteinuria and a decrease in estimated glomerular filtration rate (D’Marco et al., 2020). A molecular study revealed that the enhanced progressive decline in renal function in COVID-19 patients with diabetes mellitus could be due to upregulation of genes that influence viral infection pathways in diabetic nephropathy (Menon et al., 2020). For example, proximal tubular epithelial cell (PTEC) gene, which is co-expressed with ACE2, may exhibit cellular interplay between mechanism that enhance viral infection and host immune responses (Menon et al., 2020). Thus, COVID-19 increases the severity of the manifestations of diabetes mellitus, which may then contribute to death of the diabetic patient.