Right cut for diabetes respite

The discovery came about by accident more than a decade ago: Weight-loss surgery often led to dramatic improvement in the control of Type 2 diabetes, often before patients left the hospital.

Today, evidence of the connection is so solid that some doctors say surgery should be considered as a treatment for diabetes, regardless of a person's weight.

"This operation takes about an hour and two days in the hospital and these people go off their diabetes medication," says Dr Walter J. Pories, a professor of surgery at East Carolina University and a leading researcher on weight-loss surgery. "It is unbelievable."

Experts, however, still aren't sure why obesity surgery helps resolve Type 2 diabetes or how long the effect might last. And they disagree on how big a role surgery should have in treating the illness.

"We are going from seeing the results to understanding why it happens," said Dr Santiago Horgan, director of the Centre for the Treatment of Obesity at the University of California, San Diego.

This much is clear: Patients who have weight-loss surgery begin losing weight rapidly, which improves Type 2 diabetes, allowing diabetics to more easily control their blood glucose levels. But something else appears to be occurring as well.

There is strong evidence that surgery — especially gastric bypass surgery, which makes the stomach smaller and allows food to bypass part of the small intestine — causes chemical changes in the intestine, says Dr Jonathan Q. Purnell, director of the Bionutrition Unit at the Oregon Health & Science University. The small intestine has been thought of simply as the place where digestion occurs.

But researchers now suspect it has other functions related to metabolism. Surgery somehow alters the secretion of hormones in the gut that play a role in appetite and help process sugar normally.

Multiple studies in humans and animals indicate that surgery triggers reductions in ghrelin, the hormone that stimulates hunger, and elevates levels of peptide YY and glucagon-like peptide-1, both of which act as appetite suppressants. Another theory is that surgery might alter the expression of genes that regulate glucose and fatty-acid metabolism.

"There are these known components that improve glucose metabolism," Purnell says. "But there are very likely other things happening as well."

The effect on diabetes can depend on the type of weight-loss surgery performed, says Pories, past president of the American Society for Metabolic and Bariatric Surgery. The highest rates of diabetes remission are seen in people who have gastric bypass — about 83 per cent.

Evidence suggests the effect on diabetes can last for an extended period or even indefinitely, particularly if people don't regain a lot of weight.

"There is durability, but we also know that some people do get the disease back again," Purnell says. "If it is early on, the durability may be better."

It is not clear yet why people have different responses. "There is some evidence that African-Americans don't respond as well as Caucasians and men don't respond as well as women," Pories says.

Despite the unknowns, the evidence that a majority of people experience long-term improvement in blood glucose control suggests the surgery could eventually play a greater role in the treatment of obese people with Type 2 diabetes.

"We may have a cure for diabetes," Santiago says. "So we need to ask how medical therapies and surgery can help each other in the treatment of diabetes."

Studies from several countries show that surgery results in remission of diabetes for people who are not morbidly obese. Surgery also leads to other health benefits. Patients often see improvements in blood pressure, cholesterol, gastroesophageal reflux disease and sleep apnoea.

"Doctors say, ‘If I can lower glucose by medication, why send patients to surgery?'" Purnell says. "Surgery, however, allows people to have meaningful and sustained weight loss, and their diabetes is better. There are risks involved with surgery but it makes sense to me to do surgery."

The discovery of the gut hormones that play a role in appetite and insulin regulation may lead to new medications for Type 2 diabetes, Pories says.

"You can't operate on 31 million Americans," he says. "But if we understood this mechanism and what are the molecules secreted by the intestines that cause diabetes, then we can cure it with a pill. I would not be surprised if, in the next five years, we have new medications."