medwireNews: The humoral immune response to SARS-CoV-2 infection is similar in people with and without diabetes and is not influenced by hyperglycemia, research suggests.
These findings allow “for a cautious optimism about the efficacy of future vaccines against SARS-CoV-2 in people with diabetes,” say the study authors in Diabetologia.
The team from San Raffaele Hospital in Milan, Italy, analyzed serum samples from 509 patients with confirmed COVID-19 pneumonia who were admitted to their center between February and April 2020. In all, 27.3% of the study population had diabetes; 65.0% of these 139 patients had pre-existing diabetes, while the remaining 35.0% were newly diagnosed at the time of admission.
Lorenzo Piemonti and colleagues conducted an “extended analysis” of immunoglobulin (Ig)G, IgM, and IgA responses to the SARS-CoV-2 spike protein (receptor-binding domain [RBD] or the S1 and S2 subunits) and IgG responses to the nucleocapsid protein. They report that the responses were “superimposable” in terms of timings and antibody titers when patients were stratified according to diabetes status or by average glucose levels.
Piemonti et al note that there were “marginal differences” according to diabetes status, including a greater quantitative response of anti-RBD IgG antibodies at week 2–3 after symptom onset in people with versus without diabetes, as well as an earlier decline of IgM titers at week 3, but they stress that overall, their findings “support the evidence of an efficient humoral response in patients with diabetes.”
In accordance with previous studies, the team found that the presence of diabetes, higher mean fasting plasma glucose (FPG) levels, and greater degree of glycemic variability were all significant predictors of mortality risk on multivariate analysis. In addition, there was a significant association between average FPG levels and mortality risk among people without diabetes, with a hazard ratio (HR) of 2.39 for each 1.1 mmol/L increase.
Taken together, these findings suggest that the increased COVID-19 severity and mortality risk seen in patients with hyperglycemia is “not the result of an impaired humoral response against SARS-CoV-2,” say the study authors.
The team also evaluated associations between antibody responses and COVID-19 outcomes, finding that people with SARS CoV-2 RBD IgG antibodies had a significantly lower mortality risk than those without (HR=0.40), and this “remarkable protective effect” remained consistent when patients with (HR=0.37) and without (HR=0.43) diabetes were analyzed separately.
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