The somatostatin receptor (SSTR) family consists of five subtypes, namely SSTR1 to SSTR5, all of which are G protein-coupled receptors with seven transmembrane domains. These receptors are expressed in various tissues, including the central nervous system, gastrointestinal tract, pancreas, and immune cells. They regulate various physiological processes by binding to somatostatin, such as inhibiting hormone secretion, cell proliferation, and modulating immune responses. The activation of SSTR affects multiple signaling pathways, including cAMP, calcium ion channels, and the MAPK pathway. The tissue-specific gene expression patterns and activities determine their roles in diseases. Mutations or abnormal expression of SSTR are associated with various tumors, metabolic disorders, and immune system diseases, making them potential targets for treating these conditions.