Impact of COVID-19 Vaccination on Glycemia in Individuals With Type 1 and Type 2 Diabetes: Substudy of the COVAC-DM Study

Vaccination and potentially related side effects might impact glucose management in people with diabetes. In this study, we investigated effects of COVID-19 vaccination on glycemia assessed by continuous glucose monitoring (CGM) in people with type 1 and type 2 diabetes.
74 participants of the ongoing multicenter prospective COVAC-DM-study, investigating the immune response to COVID-19 vaccines in people with diabetes, were willing to participate in this CGM sub-study. Time spent in glycemic ranges (time in range [TIR] 70-180 mg/dL; time below range [TBR] <70 mg/dL and time above range [TAR] >180 mg/dL) was assessed daily from two days prior to three days after the first COVID-19 vaccination. Participants were asked to document side effects in response to vaccination, insulin injections, and carbohydrate intake.
58 participants with type 1 (27 female, mean age 39.5 years, HbA1c 57 ± 12 mmol/mol) and 16 with type 2 diabetes (9 females, mean age 60.6 years, HbA1c 63 ± 11mmol/mol) were included in this study. The mean TIR did not change on the day of the vaccination and the following 3 days (p>0.05). In people with type 1 diabetes, the TIR (p=0.033) and the TAR (p= 0.043) deteriorated on days with side effects as compared to those without.
Side effects occurring after COVID-19 vaccination significantly reduce the TIR and increase the TAR in people with type 1 diabetes, while no impact was observed in people with type 2 diabetes.