Reduced early response to SARS-CoV2 vaccination in people with type 1 and type 2 diabetes, a 6 months follow-up study: The CoVaDiab study I

Introduction: Diabetes mellitus worsens the prognosis of SARS-CoV-2 infection, and vaccination has been the major tool for reducing the risk of hospitalisation, and mortality. The primary aim of this study was to evaluate the response to the SARS-CoV-2 vaccine in subjects with diabetes and controls. Differences between type 1 (T1D) and type 2 (T2D) diabetes and clinical determinants of vaccination response were also evaluated. Methods: 128 subjects with diabetes (60 with T1D and 62 with T2D) and 202 subjects acting as controls who completed a full vaccination cycle with two doses of mRNA vaccine were enroled. People with previous SARS-CoV-2 infection were excluded. Antibodies (Ab) directed against the spike protein of the SARS-CoV-2 were evaluated at one and 6 months after vaccination. Results: In the whole cohort, the Ab level was higher among women than in men (p = 0.011) and negatively correlated with age (rho = -0.155, p = 0.005). Subjects with diabetes showed decreased levels of Ab after one month compared to controls (1217[747-1887]BAU/mL vs. 1477[942-2556]BAU/mL, p = 0.002), even after correction for age and gender (p = 0.002). No difference was found between subjects with T1D and T2D. After 6 months, antibody levels significantly decreased in people with and without diabetes, with no differences between groups, although some subjects were lost at follow-up. In subjects with diabetes, only a significant correlation was found between Ab level and renal function (rho 0.190, p = 0.042). Conclusions: Both T1D and T2D are associated with a reduced early response to vaccination. The serum concentration of Ab significantly reduced over time in both groups, highlighting the relevance of vaccination boosters independently of the presence of diabetes.