The immunogenicity of booster inactivated COVID-19 vaccines in patients with type 2 diabetes mellitus (T2DM) has remained unclear. Our study aims to investigate the antibody response to inactivated COVID-19 vaccine following booster vaccination in patients with T2DM.
A total of 201 patients with T2DM and 102 healthy controls (HCs) were enrolled. The levels of anti-SARS-CoV-2 total antibodies, anti-receptor-binding domain (RBD)-specific IgG, neutralizing antibody (NAb) toward SARS-CoV-2 wild type (WT), and NAb toward SARS-CoV-2 Omicron BA.4/5 subvariant were measured to evaluate the vaccine-induced immunological responses.
The titers of anti-RBD-specific IgG (p = 0.018) and inhibition rates of NAb toward WT (p = 0.007) were significantly decreased in patients with T2DM compared to HCs after booster vaccination for more than 6 months. Both HCs and patients with T2DM showed poor resistance against BA.4/5 due to the detected inhibition rates being lower than the positive threshold. The levels of anti-RBD-specific IgG were positively associated with the proportions of CD3 CD4 CD8 T cells (p = 0.045), and patients with T2DM who had anti-RBD-specific IgG positivity showed higher proportions of CD3 CD4 CD8 T cells compared to those negative (p = 0.005).
Patients with T2DM showed impaired antibody responses after booster vaccination for more than 6 months. Decreased anti-BA.4/5 responses give rise to the possibility of breakthrough infections for both patients with T2DM and HCs.

© 2023 The Authors. Journal of Diabetes published by Ruijin Hospital, Shanghai Jiaotong University School of Medicine and John Wiley & Sons Australia, Ltd.