The article discusses the study "Circadian Secretion of the Intestinal Hormone GLP-1 by the Rodent L Cell" by M. Gil-Lozano, E. L. Mingomataj, W. K. Wu and colleagues, published within the issue. Topics discussed include the influence of the day-night cylce on the glucagon-like peptide-1 (GLP-1) axis, glucose absorption from the intestine, and the rhythmicity of plasma GLP-1 concentrations.