Humoral response after breakthrough SARS-CoV-2 infection in type 2 diabetes mellitus patients

Abstract Type 2 diabetes mellitus (T2DM) remains an important public health problem in both developing and developed countries. In addition, the recent COVID-19 pandemic has revealed furthel risks for diabetes patients in terms of symptoms and disease progression. Higher mortality and morbidity are related to the complexity of the pathology of this chronic underlying disease, which negatively affects the immune response to the SARS-CoV-2 virus. The humoral response plays an important role in the eradication of the virus; thus, it was analyzed in vaccinated diabetics who underwent COVID-19, as well as in the control group. The aim of this study was to assess the prevalence and level of IgG antibodies raised against the nucleocapsid protein (NCP), S1 subunit receptor binding domain (RBD) and subunit Spike 2 (S2) subunit of the virus’s S protein using the Microblot Array test. The results demonstrated significantly lower prevalence and titers of anti-SARS antibodies in diabetic patients compared to the control group. In addition, antibody titers were negatively related to the duration of this chronic disease, body mass index (BMI), comorbidities and HbA1c concentration. Further research is needed to develop the best strategy for specific prevention of SARS-CoV-2 infection in diabetic patients.