Plays a key role in glucose metabolism and homeostasis. Regulates blood glucose by increasing gluconeogenesis and decreasing glycolysis. Potent stimulator of glucose-dependent insulin release. Plays important roles on gastric motility and the suppression of plasma glucagon levels. Stimulates intestinal growth and up-regulates villus height in the small intestine, concomitant with increased crypt cell proliferation and decreased enterocyte apoptosis. Isoform LPII is expressed in both pancreas and intestine. Expression of isoform LPI is restricted to the pancreas. Neither isoform is detected in salivary glands. Produced in the A cells of the islets of Langerhans in response to a drop in blood sugar concentration. Belongs to the glucagon family.