Admission hyperglycemia has emerged as a predictor of poor global coronavirus disease 2019 (COVID-19) outcomes. Hyperglycemia causes a decrease in the number of circulating hematopoietic stem/progenitor cells (HSPCs), which predicts diabetes complications. For a study, researchers sought to determine if decreased HSPCs mediated at least some of the predictive effect of hyperglycemia on COVID-19 outcomes. When compared to control participants (n=595), patients with COVID-19 (n=100) hospitalized in a nonintensive environment had significantly (50–60%) lower numbers of HSPCs evaluated by flow cytometry as CD34+, CD34+CD45dim, or CD34+CD133+ cells. 

The conclusion was extremely significant after multivariable correction, manual 1:1 patient matching, or propensity score matching (all P<10−10). Admission hyperglycemia (≥7.0 mmol/L) was present in 45% of patients, was linked with a substantial additional ∼30% HSPC decline, and indicated a 2.6-fold greater probability of the primary outcome of unfavorable COVID-19 course (admittance to the intensive care unit or death). Low HSPC levels were also linked to advanced age, a greater peak C-reactive protein level, and a larger neutrophil-to-lymphocyte ratio. Independent of covariates, a 1 SD decrease in CD34+ HSPCs was linked with a more than twofold increase in the probability of an unfavorable outcome. Formal analysis revealed that reducing HSPCs was a major mediator of admission hyperglycemia on COVID-19 outcome, accounting for 28% of its predictive effect.