Somatostatin affects several areas of the body. In the hypothalamus, it regulates the secretion of hormones coming from the pituitary gland, including growth hormone and thyroid stimulating hormone. In the pancreas, somatostatin inhibits the secretion of pancreatic hormones, including glucagon and insulin. Finally, in the gastrointestinal tract, the hormone reduces gastric secretion and the emission of gastrointestinal hormones, such as secretin and gastrin.

Because it is an inhibitor, somatostatin is important to balance hormone levels in the body and stop the effects of over-production of certain hormones. That means that somatostatin levels that are too low can cause the problems associated with high levels of other hormones. Growth hormone, in particular, can be problematic. However, this is a rarely reported condition.

Instead, some patients will struggle with excessive somatostatin levels when they have a specific type of endocrine tumor called a somatostatinoma. This tumor produces the hormone independently. The end result is extreme suppression of the hormones normally inhibited by somatostatin, such as insulin, which can cause major health problems.