Somatostatin, produced by pancreatic δ-cells, has been known to inhibit insulin secretion since its discovery in the 1970s. However, the role of somatostatin in the regulation of the glycaemic set point (the homeostatic blood level of glucose between meals) remains unclear. A study in Nature Metabolism now explores the contribution of pancreatic δ-cell somatostatin secretion to the glycaemic set point and β-cell insulin production.