In order to study the response of pancreatic alpha cells to the change of blood glucose, plasma pancreatic glucagon levels were measured after glucose loading given orally (50g) or intravenously (25g) in twenty-two normal controls and eighty untreated diabetics. Basal plasma pancreatic glucagon levels did not differ significantly in the two groups. However, oral or intravenous glucose administration caused a decrease in plasma pancreatic glucagon in normal subjects but not in diabetics.
In “moderate” or “severe” diabetics, plasma pancreatic glucagon tended to increase paradoxically following oral glucose loading.
To evaluate the sensitivity of pancreatic alpha cells to glucose, we calculated the index, -ΣΔIRG/ΣΔBS, after oral glucose loading. It was 1.96±0.57 in normal subjects, and significantly higher than in “mild” (0.11±0.05), “moderate” (-0.002±0.06) and “severe” (-0.09±0.07) diabetics.
These results demonstrate the insensitivity of alpha cells to hyperglycemia in patients with diabetes mellitus as compared with normal subjects.