“I believe that similar mechanisms are taking place in surgery for type-2 diabetes,” said Lam. “It strengthens the case for the surgery treating diabetes independent of weight loss.”

His rat study shows why lap banding and stomach stapling are less effective against diabetes than gastric bypass. Banding causes diabetes to go into remission in about 50 percent of patients, probably due to weight loss, said endocrinologist Dr Allison Goldfine of the Joslin Diabetes Center in Boston.

In contrast, the diabetes-remission rate after Roux-en-Y is 80 to 85 percent. “The improvements in blood glucose with Roux-en-Y appear to occur very early, by day three after surgery, so patients are being discharged with no medication,” she said. Something other than weight loss “must be going on.”

Goldfine has launched a study of diabetics with BMIs of 30 to 42 to compare outcomes after lap band surgery, Roux-en-Y, and intense medical management.

A year ago, Rubino began the first large study for type-2 diabetes patients with a BMI as low as 26, where “overweight” begins. The cost of the bypass surgery is covered by a grant from Covidien Plc, which makes laparoscopic instruments and surgical staplers. He aims to enroll at least 50 patients, following them for five years; he has operated on 20 so far.

###

By Sharon Begley

NEW YORK