Stomach surgery can reverse Type 2 diabetes even in people with severe disease, reducing or eliminating their reliance on insulin and other medicines, two highly anticipated studies reported Monday.

Surgery or surgery combined with medication helped patients more than medicine alone, the studies also found.

With the number of diabetes patients soaring in the United States, physicians are searching for new ways to combat the expensive, chronic disease that can lead to strokes, foot amputations, blindness and other problems that can reduce life expectancy by a decade or more.

The studies tested three types of surgery that reduce the size of the stomach and bypass part of the small intestine.

In the first study, conducted at the Cleveland Clinic, some 40 percent of patients who had surgery had much better control of their blood sugar, while just 12 percent of patients who did not have the operation obtained that good outcome.

The second study, conducted in Italy, achieved even better results. Gastric bypass surgery put 75 percent of patients into full remission from diabetes, while a more extreme type of surgery that bypasses more of the intestines, biliopancreatic diversion, led to a 95 percent remission rate.

“With these operations, we could take people with diabetes who are just barely obese . . . and put diabetes in full remission,” said surgeon Thomas Magnuson of Johns Hopkins University School of Medicine in Baltimore, who was not involved in either study.

Some surgeons began offering stomach surgery for diabetes in the mid-1990s, but the two new studies are the first high-quality studies that compare surgery with medical therapy. Patients in the studies were randomly selected for surgery — a hallmark of a high-quality study.

“There’s been reluctance for diabetes thought leaders to embrace surgery,” said Philip Schauer, a surgeon at the Cleveland Clinic who led one of the new studies, published online Monday in the New England Journal of Medicine.

For instance, the American Diabetes Association did not list surgery as an option in their treatment guidelines until 2009.

Schauer said surgery is now becoming more common and that the new studies highlight the best candidates: patients who try dieting, exercise and drug therapy but still have out-of-control blood sugar.

“More than 50 percent of patients with Type 2 [diabetes] are not in good blood sugar control,” Schauer said. “The current strategy is not working well for them.”

The ADA now lists surgery as an option for obese patients, as do guidelines from the National Institutes of Health. “People who have quite marked obesity who have diabetes that fails to respond to lifestyle [changes] and medication should be considered for surgery,” said Vivian Fonseca, president for medicine and science at ADA. “But it’s not for everyone.”

Heather Britton of Bay Village, Ohio, is one success story. The 57-year-old computer programmer watched relatives succumb to early deaths from the disease. And as her own diabetes progressed, her physicians heaped on medications for high cholesterol and high blood pressure on top of her diabetes pills. And yet, her blood sugar stayed high, wrecking the mental focus she needed at her job.

“It was raging out of control,” she said of her diabetes. “I felt like I was going down a predetermined path like mother and grandmother, just waiting for my stroke to happen.”

Britton had never heard of surgery for diabetes until her physician told her about the Cleveland Clinic study. Her body-mass index of 35, which is considered obese, made her eligible.

Britton had gastric bypass surgery in January 2009. By April, her doctors had taken her off all of her medications. She also began walking five days a week and eating less. She lost 80 pounds.

“It was awesome. I was feeling much better,” she says.

The downside: For Britton, certain foods, including milk, peanut butter and yeast, trigger unpleasant symptoms, like hot flashes and diarrhea — a potential side effect of the surgery.

The complication rates for surgery were low in the two studies, but a few patients did need to be reoperated on, and some suffered anemia and osteoporosis, a sign that certain nutrients were being poorly absorbed by the digestive tract.

Insurance coverage of surgery for diabetes is not universal. Most plans offer it, but others don’t. Medicaid will cover it if deemed “medically necessary,” but definitions of that vary by state. Schauer said he turns down 1,000 patients a year who could benefit from surgery but who have no way of paying the $20,000 to $25,000 the operation costs.

The studies are continuing to follow the patients for five years to see whether the benefits of surgery are sustained.

Besides reducing caloric intake and helping patients drop weight, stomach surgery also triggers hormonal changes that help patients better control blood sugar, Magnuson said.

“Some people will say it’s an extreme solution,” said Steven E. Nissen, a Cleveland Clinic cardiologist involved in the study there. “But it’s an extreme problem.”