# Metabolic and Clinical Outcomes in Type 1 Diabetes in the COVID-19 Pre- and Post-Vaccination Periods in Spain: The COVID-SED1 Study

## TL;DR

This study found that people with type 1 diabetes in Spain had slightly better blood sugar control after getting the COVID-19 vaccine.

## Contribution

The study provides new insights into the impact of the COVID-19 vaccine on glycemic control in a real-world type 1 diabetes population.

## Key findings

- HbA1c levels decreased slightly in the post-vaccination period compared to pre-vaccination.
- Glycemic control improved as measured by continuous glucose monitoring data after vaccination.
- Vaccination hesitancy was associated with lower educational levels in the T1D population.

## Abstract

Aims: To evaluate the metabolic and clinical outcomes in the Spanish type 1 diabetes mellitus (T1D) population before and after COVID-19 vaccination. Methods: A retrospective observational study was carried out in Spanish public hospitals previously enrolled in the SED1 study. Adults and children with T1D were included and their clinical electronic records were reviewed. Clinical, laboratory, and glucometric parameters from continuous glucose monitoring (CGM) data corresponding to the periods before and after administering the first COVID-19 vaccination were analyzed. Results: A total of 26 centers and 228 patients participated in this new phase of the SED1 study and 187 were finally evaluable (mean age 37.5 ± 15.6 years, 56.7% women). Overall, 94.6% of the sample was vaccinated, and this percentage increased with higher levels of education (p-value = 0.027). In the pre- and post-vaccination periods, respectively, the number of patients with acute hyperglycemic decompensation was 6/161 (3.7%) and 7/161 (4.3%) (p = 1) and with acute hypoglycemic decompensation was 6/161 (3.7%) and 6/161 (3.7%) (p = 1). The HbA1c level was lower in the post-vaccination period(mean ± SD, mg/dL): pre-vaccination 7.4 ± 0.9; post-vaccination 7.2 ± 1.0, (−0.19; p-value = 0.0006). A total of 31.9% of patients (95% CI: 24.7–39.7) in the pre-vaccination period and 45.0% (IC95%: 37.1–53.1) in the post-vaccine period had HbA1c < 7% (p-value < 0.001). Glucometrics from CGM data also showed numerical improvements post-vaccination. Conclusions: The COVID-19 vaccination was highly accepted in the Spanish T1D population, with hesitancy about the COVID-19 vaccine being higher in those with lower educational levels. A mildly better glycemic control was observed in the post-vaccination period.