Soluble Dipeptidyl-Peptidase 4 (sDPP4) Serum Activity Is Associated With the Severity of COVID-19 Disease and is a Strong Prognostic Biomarker of Mortality

Background: Type 2 diabetes mellitus (T2DM) and obesity are risk factors of COVID-19 disease course. Retrospective observational analyses reported improvement in COVID-19 severe outcomes and mortality in T2DM patients using a DPP4 inhibitor. However, little is known about the prognostic value of circulating soluble DPP4 activity in patients with SARS-CoV-2 infection. Methods: We conducted an observational, retrospective cohort study with 184 Hungarian adults. Hospitalized patients with acute COVID-19 disease (n=102) and plasma donors (n=43) recovered from prior SARS-CoV-2 infection were enrolled from April to July, 2020 at two institutions in Budapest. “Non-COVID-19 controls” (n=39) were employed with serum sDPP4 activity determined from samples taken before September, 2019. Duplicate serum sDPP4 activity determinations by microplate base enzyme kinetic assay were successful in 182 individuals from different COVID-19 disease severity groups (acute COVID-19 patients were classified into 4 and plasma donors into 2 categories based on peak severity). Findings: A significant difference in sDPP4 activity was found among study groups (p