UCLA

Type 2 diabetes is characterized by an similar to 60% loss of beta-cell mass, a marked defect in postprandial insulin secretion, and a failure to suppress postprandial glucagon concentrations. It is possible that postprandial. hyperglucagonemia in type 2 diabetes is due to impaired postprandial insulin secretion. To address this, we studied eight adult Goettingen minipigs before and after an -60% reduction in beta-cell mass induced by illoxan. Pigs were studied fasting and after ingestion of a mixed meal. Insulin and glucagon secretion were determined by deconvolution of blood hormone concentrations measured at 1-min intervals. The relationship between insulin and glucagon release was analyzed using cross-correlation and forward versus reverse cross-approximate entropy. We report that glucagon and insulin were secreted in similar to 4-min pulses. Prealloxan, postprandial insulin secretion drove an similar to 20% suppression of glucagon concentrations (P < 0.01), through inhibition of glucagon pulse mass. The alloxan-induced similar to 60% deficit in beta-cell mass lead to an similar to 70% deficit in postprandia insulin secretion and loss of the postprandial insulin-driven suppression of glucagon secretion. We conclude that postprandial hyperglucagonemia in type 2 diabetes is likely due to loss of intraislet postprandial suppression of glucagon secretion by insulin.