Data on imaging of medullary thyroid carcinoma lesions using glucagon-like peptide 1 by [Lys40(Ahx-HYNIC-99mTc/EDDA)NH2]-exendin-4 are presented by D. Pach et al. Radioactively labeled GLP-1 analogues are successfully used in patients with insulinoma but the diagnostic value in medullary thyroid cancer is not clear. Here, GCG is linked to pancreatic insulinoma.