What is the primary symptom associated with glucagonoma?

Glucagonoma is a rare pancreatic neuroendocrine tumor that primarily secretes glucagon, a hormone that plays a crucial role in glucose metabolism. The primary symptom associated with glucagonoma is hyperglycemia due to the excessive production of glucagon, which causes an increase in hepatic glucose output and leads to high blood sugar levels.

Patients with glucagonoma often present with a classic triad of symptoms which includes weight loss, diabetes mellitus (characterized by hyperglycemia), and the presence of a necrolytic migratory erythema rash. The persistent hyperglycemia is a direct consequence of glucagon's action of stimulating gluconeogenesis and glycogenolysis, overshadowing insulin's effects.

In contrast, while diarrhea may be observed in some patients due to the effects of glucagon on the gastrointestinal tract, it is not considered the primary or most defining symptom associated with glucagonoma. Other options like hypoglycemia and nephrotoxicity do not correlate with the pathophysiology of glucagonoma, making hyperglycemia the most fitting choice in this case.