Concerns about thyroid cancer with glucagon-like peptide 1 (GLP1) receptor agonist use were first raised in the premarketing phase after studies showed increased rates of thyroid C cell tumours in rodents.1 While the relevance of these findings to humans is not known, in the United States, product labels of GLP1 receptor agonists include boxed warnings about thyroid cancer and these drugs are contraindicated in patients with a personal or family history of medullary thyroid cancer or multiple endocrine neoplasia type 2. This evidence concerns the gene GLP1R and multiple endocrine neoplasia type 2.