Autoimmune diabetes mellitus after COVID-19 vaccination in adult population: a systematic review of case reports

BACKGROUND: Autoimmune/type 1 diabetes mellitus (T1DM) is a recently described rare occurrence following the administration of adjuvants such as coronavirus disease 2019 (COVID-19) vaccines. This systematic review aimed to review all available literature on the potential association between COVID-19 vaccines and T1DM. METHODS: The Directory of Open Access Journals, MEDLINE, Google Scholar, and Scopus were systematically searched for all published studies from inception to July 2022. Articles reporting T1DM development within 8 weeks of administration of COVID-19 vaccine were included. Two reviewers independently performed the risk of bias assessment following the Joanna Briggs Institute (JBI) Critical Appraisal Checklist for Case Reports. RESULTS: Eight eligible studies were retrieved, comprising 12 patients diagnosed with T1DM after being vaccinated with a COVID-19 vaccine. Six patients (50%) reported T1DM after receiving the second dose. Five patients (41.7%) presented with diabetic ketoacidosis, of which four presented within the first eight days after vaccination. Five patients (41.7%) had genetic susceptibility, with RNA binding motif protein 45 (RBM45/DRB1) and major histocompatibility complex, class II, DQ beta 1 (HLA-DQB1) mutations being prominent. INTERPRETATION: In this review, we have shown a small number of new-onset diabetes cases coincidently occurring soon after the COVID-19 vaccine, especially in those with genetic susceptibility. Despite being older, these patients had a similar phenotype to T1DM. While there might be a causal relationship between COVID-19 vaccines and T1DM development, this should not influence decisions regarding vaccination since the overall benefit outweighs the risk. Further larger prospective trials are needed to assess causal relationship and to clarify the potential roles of COVID-19 vaccine-derived antigens in autoimmune disease development. PROTOCOL REGISTRATION: PROSPERO-CRD42022342093. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12902-023-01424-0.