GCG and Hyperglycemia: GLP-1, a major incretin synthesized and secreted by intestinal L cells in response to nutrient ingestion, exerts glucoregulatory action via stimulation of glucose-dependent insulin secretion from pancreatic β-cells, inhibition of glucagon secretion from pancreatic α-cells, and deceleration of gastric emptying, attenuating postprandial hyperglycemia [176].