found that duodenal jejunum by-pass protected GK rats from beta-cell loss and hyperglycaemia which was associated
with an increased population of cells co-expressing GIP and GLP-1 in the jejunum. The intestinal bypass surgery allowed more rapid delivery of ingested nutrients to the distal bowel, which results in an increase of unabsorbed and undigested nutrients in the distal gut (Thaler & Cummings, 2009)