Acromegaly: insensitivity of the pancreatic alpha cell to hyperglycaemia.

Plasma glucagon levels were determined after 50 g of oral glucose loading in eleven acromegalics and fourteen normal subjects. Basal plasma glucagon levels were significantly elevated in patients with acromegaly, as compared with those in normal subjects. Oral glucose loading caused a decrease in plasma glucagon in normal subjects but not in acromegalics. Since this non-suppressibility of plasma glucagon by orally administered glucose was observed even in acromegalics without diabetes, it is concluded that insensitivity of the pancreatic alpha cell to hyperglycaemia exists in patients with acromegaly as well as in diabetics.