Tirzepatide decreases body weight while improving glucose metabolism in patients with obesity and type-2 diabetes. Although the drug is designed to activate the receptors for glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP), the contribution of the GIP receptor to its metabolic effects is not yet fully understood. A team of researchers demonstrated for the first time that tirzepatide stimulates insulin secretion in the human pancreas via the GIP receptor. These results contrast with findings in mice, where tirzepatide primarily stimulated insulin secretion with the GLP-1 receptor. This study is now published in Nature Metabolism.