Abstract
Background: Endocrine disturbances are increasingly recognized as components of long COVID, yet long-term data remain limited. This study evaluated the prevalence of dysglycemia and thyroid autoimmunity four years after SARS-CoV-2 infection in adults without previously known endocrine disease. Methods: We conducted a retrospective longitudinal 4-year evaluation of adults hospitalized for COVID-19 between 2020 and 2021. Of 1009 eligible patients without prior diabetes or thyroid disease, 96 completed a standardized 4-year post-infection evaluation. Acute-phase data included COVID-19 severity, admission glucose, inflammatory markers, imaging findings, and treatments. The 4-year evaluation comprised fasting plasma glucose, thyroid function tests, anti-thyroid antibodies (anti-TPO, anti-Tg), and thyroid ultrasonography. Baseline HbA1c, thyroid autoantibodies, and thyroid imaging were not available. Results: At four years post-infection, 27.1% of patients exhibited dysglycemia compatible with type 2 diabetes mellitus, 41.6% showed thyroid autoimmunity, and 15.6% presented with both conditions. Overall, 47.9% developed at least one endocrine alteration. Admission hyperglycemia strongly predicted long-term dysglycemia (OR 6.67; 95% CI: 1.45–30.58), and diabetes prevalence increased with acute disease severity. Thyroid autoimmunity was frequent but not associated with initial COVID-19 severity. Conclusions: Four years after SARS-CoV-2 infection, a substantial proportion of patients exhibited persistent metabolic and autoimmune alterations, supporting a long COVID immunometabolic phenotype. In the absence of baseline endocrine data, the reported findings reflect long-term endocrine alterations identified at the 4-year evaluation, with a potential role of SARS-CoV-2 infection. These findings highlight the importance of baseline metabolic and thyroid assessment—including HbA1c and thyroid autoantibodies—in hospitalized COVID-19 patients and underscore the need for structured long-term endocrine monitoring.