I found an interesting study on gastric bypass and diabetes at this link.
Scientists tested the insulin levels of 2 groups of diabetics: one group underwent gastric bypass surgery, the other group lost a similar amount of weight through calorie restriction alone.
Patients from both groups were matched for age, body weight, body mass index, diabetes duration and control, and amount of weight loss.
So the only variable was how they lost weight. And the results were somewhat surprising.
There was marked improvement in the levels tested for the gastric bypass patients, but not for the diet patients.
So the scientist drew the conculsion that, “early after GBP, the greater GLP-1 and GIP release and improvement of incretin effect are related not to weight loss but rather to the surgical procedure. This could be responsible for better diabetes outcome after GBP.”
In other words, having a gastric bypass is actually a more effective treatment for diabetes than weight loss alone. It’s just another in the long list of gastric bypass surgery benefits.