Immediate impacts of COVID-19 vaccination on glycemic control in type 1 diabetes mellitus: a systematic review and meta-analysis.

Objective: COVID-19 vaccination is recommended in diabetic patients since diabetes is associated with worse clinical outcomes in COVID-19 infection. The safety profile of different types of COVID-19 vaccines, especially on glycemic control, can be explored due to availability of data from continuous glucose monitoring (CGM) devices. This meta-analysis aimed to quantify the impact of COVID-19 vaccination on glycemic control in patients with type 1 diabetes mellitus (T1DM).

Methods: A systematic search of PubMed, Embase, and Google Scholar was conducted using a search strategy for studies published till January 2023 in English language. Comparative observational studies reporting glycemic control obtained from CGM before and after COVID-19 vaccination in T1DM patients were included. The primary outcome was time in range (TIR) metric of proportion of glucose results falling within the range: 3.9-10 mmol/l. Other outcomes were time above range (TAR) (>10 mmol/l), time below range (TBR) (<3.9 mmol/l), coefficient of variation (CV), and mean blood glucose levels. The pooled outcomes were compared pre-vaccination and post-vaccination using Hedges' g (HG) with 95% CI.

Results: A total of seven studies (632 participants) were included in the meta-analysis. COVID-19 vaccination caused small and statistically insignificant decrease in TIR after both the first (HG = 0.21, 95% CI: -0.02 to 0.44, =0.07) and second dose (HG = 0.09, 95% CI: -0.04 to 0.21, = 0.19). Likewise, TAR was not affected after neither first (HG = -0.09, 95% CI: -0.22 to 0.03, = 0.12) nor second vaccine dose (HG = -0.07, 95% CI: -0.21 to 0.06, = 0.30). Likewise, TBR, mean blood glucose levels, and CV were not significantly altered following uptake of either of the doses.

Conclusion: COVID-19 vaccination has an excellent safety profile in T1DM patients owing to its minimal impacts on immediate glycemic control.