Bariatric Reversal: Stomach surgery curbs some patients’ diabetes

In obese people with diabetes, stomach surgery to control hunger may do more than induce weight loss. A study now finds it can send their diabetes into remission.

Australian researchers enlisted 60 obese people diagnosed in the previous 2 years with mild type 2, or adult-onset, diabetes. Only one study participant needed insulin. The researchers randomly assigned some participants to receive bariatric surgery along with any necessary diabetes drugs. Others got medication alone. Two years later, 22 of the 30 patients who underwent the operation showed no signs of diabetes and didn’t need diabetes drugs, compared with only 4 of the 30 assigned to medication alone, the researchers report in the Jan. 23 Journal of the American Medical Association.

“This is a real landmark study,” says surgeon Philip Schauer of the Cleveland Clinic. It’s the first scientifically rigorous trial to show that surgery can treat type 2 diabetes, he says.

Patients getting surgery lost an average of 20 percent of their body weight, while those getting only medication lost less than 2 percent, says study coauthor John B. Dixon, a physician at Monash University in Melbourne. The dramatic weight loss led to better control of blood glucose levels, he says.

Many obese people aren’t eligible for bariatric surgery, despite its solid record of inducing weight loss. In 1991, the National Institutes of Health established that anyone with a body mass index (BMI) of 40 or more would qualify for bariatric surgery, as would those with a BMI of at least 35 if they also had a related health condition such as diabetes. People with a BMI over 25 are considered overweight and, if over 30, obese.

BMIs of participants in the new study ranged from 30 to 40. The results suggest that people with diabetes in the 30–35 BMI range would benefit from the surgery, says Schauer.

The researchers used gastric banding, in which surgeons perform minimally invasive surgery to bind the upper part of a patient’s stomach like an hourglass. The other main bariatric surgery, gastric bypass, is a more invasive operation that reconfigures the anatomy to shunt food from the stomach to the small intestine.

While both procedures curb appetite, bypass surgery also induces the intestines to make more GLP-1, a hormone that stimulates insulin secretion and regulates blood glucose. Bypass surgery might reverse diabetes even better than banding, Dixon says.

Earlier studies have hinted that, in obese people, type 2 diabetes that has gone on for more than 5 years is unlikely to be reversible, even with surgery, says Jaime Ponce, a surgeon at the Hamilton Medical Center in Dalton, Ga. By that time, the pancreas’ insulin-making cells are too damaged. This study supports the notion that there is a window of time, probably less than 5 years, when surgery can reverse diabetes, Ponce says.