Skrha determined the plasma concentrations of selected gastrointestinal hormones (GIP, GLP-1, PP, peptide YY (PYY), and neuropeptide Y (NPY), as well as cytokines, leptin, and adiponectin) in PDAC patients with and without diabetes and compared them with the levels found in type 2 diabetic patients without cancer. This evidence concerns the gene GCG and diabetes mellitus.