Pre-vaccination glucose time in range correlates with antibody response to SARS-CoV-2 vaccine in type 1 diabetes

Context: Poor glucose control has been associated with increased mortality in COVID-19 patients with type 1 diabetes (T1D). Objective: To assess the effect of pre-vaccination glucose control on antibody response to the SARS-CoV-2 vaccine BNT162b2 in T1D. Design and methods: We studied 26 patients with T1D scheduled to receive two doses, 21 days apart, of BNT162b2, followed prospectively for six months with regular evaluation of SARS-CoV-2 antibodies and glucose control. IgG to spike glycoprotein were assessed by ELISA, and serum neutralization by a live SARS-CoV-2 assay (Vero E6 cells system). HbA1c and continuous glucose monitoring (CGM), including time in range (TIR) and above range (TAR) were collected. Main outcome measures: The primary exposure and outcome measures were pre-vaccination glucose control, and antibody response after vaccination, respectively. Results: Pre-vaccination HbA1c was unrelated to post-vaccine spike IgG (r = -0.33, p = 0.14). Of note, the CGM profile collected during the two weeks preceding BNT162b2 administration, correlated with post-vaccine IgG response (TIR: r = 0.75; p = 0.02; TAR: r = -0.81; p = 0.008). Patients meeting the recommended pre-vaccination glucose targets of TIR (≥70%) and TAR (≤25%), developed stronger neutralizing antibody titres (p < 0.0001 and p = 0.008, respectively), regardless of HbA1c. Glucose control along the study timeframe was also associated with IgG response during follow-up (TIR: r = 0.93, p < 0.0001; TAR: r = -0.84, p < 0.0001). Conclusions: In T1D, glucose profile during the two weeks preceding vaccination is associated with stronger spike antibody binding and neutralization, highlighting a role for well-controlled blood glucose in vaccination efficacy.