First, the rapid delivery of nutrients to thelower intestine from the gastrointestinal bypass increases the stimulation of L-cells, whichresults in increased secretion of hormones that enhance insulin release and/or insulin action(for example, glucagon-like peptide-1), and a subsequent decrease in blood glucose levels.Second, gastrointestinal bypass reduces the secretion of upper gastrointestinal factors thatdecrease insulin secretion and/or promote insulin resistance. The gene discussed is GCG; the disease is Insulin resistance.