Studies in rodents indicate that GLP-1RAs promote thyroid C-cell hyperplasia and medullary thyroid carcinoma (MTC) by a GLP-1R mediated increase in calcitonin synthesis.33 High levels of fasting serum insulin and insulin resistance are associated with an increased risk of thyroid cancer.34 Although clinical evidence for an association of thyroid cancer with the use of GLP-1RAs has been reported as inconclusive,35 the findings from our study together with previous reports of insulins promoting cancer growth suggest that GLP-1RAs might be associated with increased risk of thyroid cancer. This evidence concerns the gene GLP1R and medullary thyroid gland carcinoma.