GCG and type 2 diabetes mellitus: Several studies on the potential mechanisms involved in the rapid control of type 2 diabetes in obese patients after certain surgical interventions have shown that exclusion of the duodenum and the upper part of the jejunum and the more rapid emptying of ingested nutrients into the distal ileum induce significant changes in gastrointestinal hormones such as incretins that are involved in insulin secretion and glucose regulation [28–31].