Diagnosis of latent autoimmune diabetes after SARS–Cov2 vaccination in adult patients previously diagnosed with type 2 diabetes mellitus

Objective Acute worsening of glycemic control in diabetic patients and new–onset type I diabetes were reported after severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccines. Latent autoimmune diabetes in adults (LADA) is defined as a slowly evolving immune–mediated diabetes. A few cases of LADA diagnosed after SARS-CoV-2 vaccination have been reported in the literature. This study aims to report LADA after mRNA-based SARS-CoV-2 vaccinations in subjects with a history of well-controlled type 2 diabetes. Methods We report four cases with LADA diagnosed after mRNA-based SARS-CoV-2 vaccine, BNT162b2 (Pfizer-BioNTech). In the medical history, all subjects had well-controlled type 2 diabetes with oral anti-diabetic medication. One case had autoimmune thyroid disease. One subject was presented with diabetic ketoacidosis. Results Glycemic control of the presented cases had deteriorated 6–10 weeks after BNT162b2 vaccination. All patients were male and had high levels of glutamic acid decarboxylase 65 antibody (GAD65ab). An intensive insulin regimen was initiated at the time of diagnosis. The need for insulin therapy in two patients disappeared during follow-up. Two subjects were managed with basal insulin and oral antidiabetics. GAD65ab disappeared just 1 year after the diagnosis of LADA in a subject. Conclusion In case of impaired glycemic control after SARS-CoV-2 vaccination in a well-controlled diabetic patient, LADA should be considered.