Weight loss surgery, which in recent years has been seen as an increasingly attractive option for treating Type 2 diabetes, may not be as effective against the disease as it was initially thought to be, according to a new report. The study found that many obese Type 2 diabetics who undergo gastric bypass surgery do not experience a remission of their disease, and of those that do, about a third redevelop diabetes within five years of their operation.
The findings contrast with the growing perception that surgery is essentially a cure for Type II diabetes. Earlier this year, two widely publicized studies reported that surgery worked better than drugs, diet and exercise in causing a remission of Type 2 diabetes in overweight people whose blood sugar was out of control, leading some experts to call for greater use of surgery in treating the disease. But the studies were small and relatively short, lasting under two years.
The latest study, published in the journal Obesity Surgery, tracked thousands of diabetics who had gastric bypass surgery for more than a decade. It found that many people whose diabetes at first went away were likely to have it return. While weight regain is a common problem among those who undergo bariatric surgery, regaining lost weight did not appear to be the cause of diabetes relapse. Instead, the study found that people whose diabetes was most severe or in its later stages when they had surgery were more likely to have a relapse, regardless of whether they regained weight.
“Some people are under the impression that you have surgery and you’re cured,” said Dr. Vivian Fonseca, the president for medicine and science for the American Diabetes Association, who was not involved in the study. “There have been a lot of claims about how wonderful surgery is for diabetes, and I think this offers a more realistic picture.”
The findings suggest that weight loss surgery may be most effective for treating diabetes in those whose disease is not very advanced. “What we’re learning is that not all diabetic patients do as well as others,” said Dr. David E. Arterburn, the lead author of the study and an associate investigator at the Group Health Research Institute in Seattle. “Those who are early in diabetes seem to do the best, which makes a case for potentially earlier intervention.”
One of the strengths of the new study was that it involved thousands of patients enrolled in three large health plans in California and Minnesota, allowing detailed tracking over many years. All told, 4,434 adult diabetics were followed between 1995 and 2008. All were obese, and all underwent Roux-en-Y operations, the most popular type of gastric bypass procedure.
After surgery, about 68 percent of patients experienced a complete remission of their diabetes. But within five years, 35 percent of those patients had it return. Taken together, that means that most of the subjects in the study, about 56 percent — a figure that includes those whose disease never remitted — had no long-lasting remission of diabetes after surgery.
The researchers found that three factors were particularly good predictors of who was likely to have a relapse of diabetes. If patients, before surgery, had a relatively long duration of diabetes, had poor control of their blood sugar, or were taking insulin, then they were least likely to benefit from gastric bypass. A patient’s weight, either before or after surgery, was not correlated with their likelihood of remission or relapse.
In Type 2 diabetes, the beta cells that produce insulin in the pancreas tend to wear out as the disease progresses, which may explain why some people benefit less from surgery. “If someone is too far advanced in their diabetes, where their pancreas is frankly toward the latter stages of being able to produce insulin, then even after losing a bunch of weight their body may not be able to produce enough insulin to control their blood sugar,” Dr. Arterburn said.
Nonetheless, he said it might be the case that obese diabetics, even those whose disease is advanced, can still benefit from gastric surgery, at least as far as their quality of life and their risk factors for heart disease and other complications are concerned.
“It’s not a surefire cure for everyone,” he said. “But almost universally, patients lose weight after weight loss surgery, and that in and of itself may have so many health benefits.”
