How does the gastric bypass and biliopancreatic diversion cure diabetes prior to weight loss?
This is more complex than calorie restriction and involves changes in gut hormones. Bypassing the duodenum and proximal jejunum (the proximal gut theory) changes gastric inhibitory polypeptide hormone levels and likely other as yet unknown hormonal levels that play a role in the incretin effect. The hindgut theory is based on the hypothesis that food now reaches the terminal ileum and colon faster, resulting in a greater activation and release of other hormones, namely glucagon-like peptide 1 and peptide YY 3-36, which result in greater insulin secretion and sensitivity.
Can these changes in the gut hormonal milieu have a detrimental effect?
Although these changes are only beginning to be understood, the rare hyperinsulinemic hypoglycemia and apparent beta cell hyperplasia seen years after a gastric bypass may be due to hormonal overstimulation of the pancreas.