HbA1c Level in Severe COVID-19 Patients Is Not Only a Marker of Glycemic Status but Also of Acute Erythrocyte Damage

Shestakova, Marina V.; Kononenko, Irina Kalmykova Zilya Zheleznyakova Anna Mokrysheva Natalia

Introduction: COVID-19 can trigger either transient stress-induced state, or newly onset diabetes mellitus (DM). It is well known that HbA1c serves as an indicator of glycemic status 12 weeks before the acute disease. Aim: To examine glycemic status at admission and 6 weeks after hospital discharge in patients with confirmed COVID-19 but no previous DM-history. Methods: Of 155 patients hospitalized with COVID-19 and pneumonia 111 persons had no previous DM-history. The levels of HbA1с, fasting and admission plasma glucose (FPG and APG) were measured at admission and 6 weeks after the discharge. The severity of COVID-19 was confirmed by CT scan, SpO2, serum IL-6, CRP, D-dimer. Results: All 111 patients had normal FPG and APG values. According to HbA1c level all the patients were divided into two groups: A) HbA1c≤6.0% (n=64, median 5,8%) and B) HbA1c>6,0% (n=47, median 6,4%). Our particular interest was focused on the group B due to the discrepancy of high HbA1c level and normal FPG and APG. Group B patients were retested for glycemic status in 6±1 week after the discharge. Surprisingly the median HbA1c level dropped down from 6,4% to 5,7% in such a short period of time with no antidiabetic drugs. COVID-19 severity markers were significantly higher in the group B. Conclusions: We suggest two explanations for this faster than expected HbA1c decrease: 1) patients with HbA1c>6,0% will progress to DM later, and, therefore, a longer follow-up is needed;2) SARS-CoV-2 virus has extensively glycosylated spike(S)-protein that may bind to erythrocytes. High-pressure liquid chromatography (the standard method for HbA1c) probably fails to separate the glycated 1-β-chain of hemoglobin from glycated viral spikes. In this case, abnormally high HbA1c in COVID-19 patients with no DM-history may serve as a marker of severe viral erythrocyte damage rather than a marker for the glucose control. This hypothesis is confirmed by the prompt (in 6 weeks) normalization of HbA1c level following the virus elimination.