Abstract
In order to investigate the relationship between the characteristic triphasic blood sugar response and plasma insulin in the initial period of alloxan diabetes, the levels of blood sugar, plasma immunoreactive insulin and non-esterified fatty acid (NEFA) were measured frequently for two to seven days following the intravenous administration of alloxan (100 mg/kg) in dogs.
1) During the initial phase of hyperglycemia, plasma insulin did not change significantly while NEFA increased.
2) In the hypoglycemic phase, plasma insulin increased markedly about two to ten times as high as the control level. The change in plasma insulin was inversely related to the blood sugar level.
Despite the rise in plasma insulin, NEFA did not decrease but tended to rise.
3) When the persistent hyperglycemia developed, plasma insulin level fell significantly below the control level and remained unchanged after 48 hours. NEFA continued to rise.
These results seem to suggest that there is some inhibition of extra-secretion of insulin despite hyperglycemia during the initial phase, and provide support for the view of uncontroled release of insulin during the hypoglycemic phase. Persistent hyperglycemia is apparently due to the deficiency of circulating insulin although the deficiency seems to be incomplete.
