The new arrangement of the gut created by obesity surgery helps to explain the procedure’s power to relieve type 2 diabetes.
Obesity surgery, which severely restricts the amount of food that can be held in the stomach, also raises the body’s production of the digestive hormone insulin. This extra insulin helps to lower the dangerously high blood sugar levels of surgery recipients with type 2 diabetes.
Fiona Gribble at the Wellcome Trust MRC Institute of Metabolic Science in Cambridge, UK, and her colleagues studied lean people who had undergone a cancer-treatment procedure similar to obesity surgery. After study participants drank a sugary beverage, their insulin levels soared. When they drank the sweet solution while also receiving a compound that blocks the action of the hormone GLP-1, however, the change in their insulin levels was much less marked, showing that GLP-1 has a role in post-surgical insulin spikes.
The team also found that because obesity surgery re-arranges the gut, large quantities of nutrients are absorbed further along the intestines than normal. As a result, the nutrients reach GLP-1-producing cells deep in the gut, which respond by churning out large amounts of GLP-1.