SARS-CoV-2 booster vaccination does not worsen glycemia in people with type 1 diabetes using insulin pumps: an observational study

Despite an increased risk for adverse outcomes from SARS-CoV-2 infection among individuals with type 1 diabetes (T1D), vaccine hesitancy persists due to safety concerns including dysglycemia. The impact of booster vaccination on individuals using automated insulin delivery (AID) systems remains unclear.

We used continuous glucose monitoring (CGM) data from 53 individuals with T1D using insulin pump therapy who received their third and/or fourth COVID-19 vaccination. CGM data from the 14 days before and 3 and 7 days after each vaccination were compared. The primary outcome was glucose time in range (TIR) (70–180 mg/dL) 3 and 7 days post-vaccination compared with the 14 days prior. Secondary outcomes included other CGM metrics such as time below range (< 70 mg/dL), time above range (> 180 mg/dL), mean glucose, co-efficient of variation and average total daily insulin.

The cohort comprised 53 adults (64% women, 64% AID), totaling 74 vaccination periods (84% Pfizer-BioNTech boosters), mean ± SD age 40.0 ± 15.9 years, duration of diabetes 26.0 ± 15.4 years. There was no significant difference between pre-vaccination TIR (61.0%±18.5) versus 3 (60.5%±22.8) and 7 days post-vaccination (60.2%±21.8; p = 0.79). Level 1 hypoglycemia, time in range 54–69 mg/dL, was lower 3 (1.1%±1.7) and 7 days post-vaccination (1.1%±1.6), compared with 14 days pre-vaccination (1.4%±1.4; p = 0.021).

The study provides evidence that SARS-CoV-2 booster vaccination does not acutely worsen glycemia in people with T1D receiving insulin pump therapy.