The study, led by researchers at the Cleveland Clinic, followed 150 patients, one-third of whom were treated for their diabetes with medication and lifestyle changes alone; one-third who also got gastric bypass surgery; and one-third who had a different type of bariatric surgery called a sleeve gastrectomy.
All three groups were overweight or mildly obese and had diabetes that was not well controlled by medication. Type 2 diabetes, the most common form, is connected to and often driven by excess weight.
Three years later, the patients who had surgery had nearly normal levels of blood sugar while taking less medication than the group on medication alone, said study co-author Philip Schauer, a surgeon and director of the Cleveland Clinic's Bariatric and Metabolic Institute.
"At three years, the therapeutic gap — the difference between blood sugar in the surgical group and the medical group — got even larger in favor of surgery" than it had been at one year, he said. Diabetes got worse in the group taking medications alone, as is typical with diabetic patients, said Schauer, whose study was presented today at the American College of Cardiology's annual conference in Washington, D.C., and appears in the New England Journal of Medicine.
Researchers still don't understand exactly why obesity surgery is so effective against diabetes. The improvements begin almost immediately. Patients who needed insulin to treat their diabetes the morning before surgery didn't need it anymore by the time they left the hospital a day or two later, Schauer said.
The trial, known by the acronym STAMPEDE, also showed that the two types of surgery had fairly similar benefits, which was somewhat unexpected because gastric bypass has been around longer and was believed to be better.
Noel Williams, head of the Metabolic & Bariatric Surgery Program at the Hospital of the University of Pennsylvania, said he's seeing the same thing in his patients.
Both surgeries are performed through tiny entries into the body, but sleeve gastrectomy is a more modest surgery, in which doctors essentially shrink the size of the stomach by about 70%. In gastric bypass, there is more rerouting of the system, with a greater chance of leaks, ulcers and dangerous narrowing of passageways, Williams said. Both usually involve one to two nights in the hospital and cost about $20,000 on average, he said.
Insurance generally only covers the procedure for people with a body mass index, or BMI, over 35 — heavier than the people in this study — which Williams said needs to change. BMI is a measure that factors both weight and height.
"If you can cure diabetes by an operation like this and maintain that cure rate, then it's a good investment" for the insurance company to pay for the surgery, Williams said.
Schauer said he hopes to have detailed numbers on the financial advantages of surgery when he updates the STAMPEDE trial in another two years, five years after the patients have had their surgery. By then, he thinks the savings from reducing their medications will outweigh the costs of the surgery.
The trial was funded in part by a grant from Ethicon, a Johnson & Johnson company that makes equipment used in bariatric surgery.