Which paracrine regulator of insulin and glucagon is produced by delta cells of the pancreas?

• A. Somatostatin
• B. Insulin
• C. Glucagon
• D. Ghrelin

Answer: (A)

Delta cells in the pancreatic islets secrete somatostatin, which acts locally (paracrine) to modulate neighboring cells' hormone release. Somatostatin inhibits both insulin from beta cells and glucagon from alpha cells, helping to smooth out rapid changes in blood glucose after meals. This local regulation keeps glucose levels from spiking too high or dropping too low.

Insulin and glucagon are produced by different islet cells—beta cells and alpha cells, respectively—so they are not delta cell products. Ghrelin is primarily produced in the stomach (with minor pancreatic sources), not by delta cells.