Type 1 Diabetes Mellitus Caused by COVID-19 mRNA Vaccination: A Case Report and Literature Review of 17 Published Cases

Background/ObjectiveMultiple cases of post-vaccination immune-related adverse events have been reported. We, hereby, present a patient who presented with new onset type 1 diabetes mellitus after COVID-19 mRNA vaccination.Case ReportA 38-year-old Caucasian man presented with sudden onset of polyuria, polydipsia, and blurry vision for one month. The patient received the second dose of the COVID-19 mRNA vaccine (Pfizer-BioNTech) four weeks prior to symptom onset. Initial workup revealed glucosuria and HbA1c of 9.4%. Antibodies against multiple pancreatic beta cell autoantigens were detected. The patient was then initiated on insulin.DiscussionHypothesized mechanisms for development of type 1 diabetes mellitus after COVID-19 mRNA vaccination include molecular mimicry, autoimmune/inflammatory syndrome induced by adjuvants, and possible interaction between the ACE2 receptor on beta cells and viral mRNA. An initial high index of suspicion should be accompanied by early autoantibody testing and initiation of insulin, if indicated. Finally, if diagnosed with type 1 diabetes, patients must have long-term follow-up as there may be brief periods where glycemic control is maintained off insulin.ConclusionNew onset type 1 diabetes mellitus has been reported after COVID mRNA vaccination. Clinicians should maintain a high index of suspicion and pursue early testing for the same to reduce adverse outcomes and improve long term prognosis.