# The Thyroid Twist: How GLP-1 Agonists Are Influencing Autoimmune Thyroid Care

## TL;DR

This paper reviews how GLP-1 agonists, used for diabetes and obesity, may also affect autoimmune thyroid diseases by modulating immune and metabolic pathways.

## Contribution

It synthesizes emerging evidence on GLP-1RAs' immunomodulatory effects and their potential therapeutic implications for autoimmune thyroid disease.

## Key findings

- GLP-1RAs may influence autoimmune thyroid disease through immunomodulatory and metabolic effects.
- Preliminary reports suggest GLP-1RAs could impact thyroid volume, function, and autoimmune activity.
- Safety concerns include potential risks of thyroid C-cell tumors and adjustments in thyroid hormone therapy.

## Abstract

Autoimmune thyroid disease (AITD), including Hashimoto thyroiditis and Graves’ disease, represents the most prevalent organ-specific autoimmunity and a major cause of thyroid dysfunction worldwide. Increasingly, AITD coexists with metabolic disorders such as obesity, insulin resistance, and metabolic dysfunction-associated steatotic liver disease (MASLD), suggesting an interplay between immune dysregulation and metabolic health. Glucagon-like peptide-1 receptor agonists (GLP-1RAs), such as semaglutide and tirzepatide, have emerged as transformative agents for type 2 diabetes and obesity through their potent effects on weight reduction, insulin sensitivity, and cardiovascular outcomes. Beyond these metabolic benefits, accumulating evidence indicates that GLP-1RAs exert immunomodulatory effects, including suppression of pro-inflammatory cytokines, enhancement of regulatory T-cell function, and improvements in adipose tissue and gut-derived immune signaling.

Although dedicated trials of GLP-1RAs in AITD are lacking, preliminary reports suggest potential impact on thyroid volume, thyroid function, and autoimmune activity. Mechanistic hypotheses include reduced leptin-driven T-helper (Th)1/Th17 activity, improved adipokine balance, and modulation of gut-thyroid axis pathways. Potential benefits must be weighed against safety considerations, including theoretical risks of thyroid C-cell tumors from animal studies and the need for careful adjustment of thyroid hormone therapy in patients experiencing significant weight loss.

This review synthesizes the current understanding of AITD pathophysiology, summarizes emerging evidence on the immunometabolic effects of GLP-1RAs, and explores potential therapeutic implications for patients with concurrent thyroid autoimmunity and metabolic disease. Rigorous clinical and translational studies are needed to clarify the role of GLP-1RAs in the management of AITD.