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

Multiple cases of postvaccination immune-related adverse events have been reported. We, hereby, present a patient who presented with new-onset type 1 diabetes mellitus (DM) after COVID-19 messenger RNA (mRNA) vaccination.

A 38-year-old Caucasian man presented with sudden onset of polyuria, polydipsia, and blurry vision for 1 month. The patient received the second dose of the COVID-19 mRNA vaccine (Pfizer-BioNTech) 4 weeks prior to symptom onset. Initial workup revealed glucosuria and hemoglobin A1c of 9.4%. Antibodies against multiple pancreatic beta cell autoantigens were detected. The patient was then initiated on insulin.

Hypothesized mechanisms for development of type 1 DM after COVID-19 mRNA vaccination include molecular mimicry, autoimmune/inflammatory syndrome induced by adjuvants, and possible interaction between the angiotensin-I converting enzyme-2 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.

New-onset type 1 DM 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.