From the Guidelines
Diabetes in somatostinoma occurs due to the tumor's excessive secretion of somatostatin, which inhibits insulin release and leads to impaired glucose metabolism. The mechanisms behind this include direct suppression of insulin secretion from pancreatic beta cells, slowed gastrointestinal motility, reduced nutrient absorption, and inhibition of hormones like glucagon-like peptide-1 (GLP-1) that stimulate insulin secretion 1. This results in a state of insulin deficiency and glucose intolerance, manifesting as diabetes mellitus. Key aspects of somatostinoma-induced diabetes include:
- Direct inhibition of insulin secretion by somatostatin
- Impaired glucose metabolism due to reduced insulin levels
- Slowed gastrointestinal motility and reduced nutrient absorption affecting postprandial glucose regulation
- Inhibition of GLP-1 release, further reducing insulin secretion
The diabetes associated with somatostinoma is typically mild to moderate in severity and may be part of a clinical syndrome that includes diarrhea, steatorrhea, gallstones, and weight loss, known as the "somatostatinoma syndrome" 1. Management of somatostinoma and its associated diabetes involves addressing the underlying hormonal imbalance, which may include the use of somatostatin analogues like octreotide and lanreotide to control symptoms and improve quality of life 1. The use of long-acting formulations of somatostatin analogues is considered the standard of care for symptomatic treatment of neuroendocrine tumors, including somatostinoma.
From the Research
Diabetes in Somatostatinoma
- Diabetes mellitus is a common clinical presentation of somatostatinoma, a rare endocrine tumor that originates from the pancreas or duodenum 2.
- The tumor secretes excessive amounts of somatostatin, which suppresses the secretion of insulin and glucagon, leading to hyperglycemia 3, 4.
- The inhibitory effect of somatostatin on insulin and glucagon secretion can cause mild nonketotic hyperglycemia, hypochlorhydria, cholelithiasis, steatorrhea, anemia, and weight loss, characterized as the somatostatinoma "inhibitory syndrome" 3, 5.
- In some cases, somatostatinoma can present with diabetic ketoacidosis, which is thought to arise from the secretion of larger molecular weight forms of somatostatin from the tumor 3.
- The relationship between somatostatinoma and diabetes is complex, and the tumor's effects on glucose homeostasis can vary depending on the location and type of tumor, as well as the presence of other underlying conditions 6, 2.
Pathophysiologic Mechanisms
- Somatostatin's inhibitory effect on insulin and glucagon secretion can lead to impaired glucose regulation and hyperglycemia 4.
- The tumor's secretion of somatostatin can also suppress the secretion of other hormones, such as growth hormone, which can further contribute to glucose dysregulation 4.
- The underlying pathophysiologic mechanisms of somatostatinoma-related diabetes are not fully understood and require further study 3, 2.
Clinical Presentation and Management
- Somatostatinoma can present with a range of clinical symptoms, including diabetes mellitus, cholelithiasis, steatorrhea, abdominal pain, and obstructive jaundice 2, 5.
- The management of somatostatinoma-related diabetes typically involves surgical removal of the tumor, as well as medical management of glucose levels and other related symptoms 6, 2.