Cristina Iaboni had the dubious distinction of being not quite obese enough. For all the pounds on her 5’5” frame, she did not meet the criteria for bariatric surgery to help control her type-2 diabetes.

Yet six years of medications and attempts at healthy living had failed to rein in her blood glucose, leaving Iaboni terrified that she was on course to have her kidneys fail “and my feet cut off” - common consequences of uncontrolled diabetes.

Then the 45-year-old Connecticut wife, mother of two and head of human resources for a Fortune 500 company, lucked out. In 2009 she met with Dr Francisco Rubino of Weill Cornell Medical Center in New York. He had just received approval to study experimental surgery on diabetics with a relatively lean weight-to-height ratio, or body-mass index (BMI). Iaboni was among his first subjects.

Three years on, she has dropped 50 pounds to reach a healthy 145 and has normal blood pressure without medication. That isn’t too surprising: Weight loss is the purpose of bariatric surgery and often reduces blood pressure. More remarkable, Iaboni no longer has diabetes.

She is not the first patient with diabetes, which can be triggered by obesity, to be cured by weight-loss surgery. But she is a rarity for having it with a BMI well below 35 and over. That’s the level at which the American Diabetes Association says surgery “may be considered” and that Medicare and some private insurers cover. And Iaboni’s diabetes disappeared months before she shed much weight.

Her experience has raised an intriguing possibility: that some forms of bariatric surgery treat diabetes not by making patients shed pounds. Instead, by rerouting part of the digestive system, they change what signals the gut sends to the brain and the brain sends to the liver, altering the underlying causes of diabetes.

If proven, bariatric surgery may help people with type-2 diabetes who are less obese, overweight or even of healthy weight. And it might be effective against the currently incurable type-1, or “juvenile,” diabetes, too.

“Every textbook says that diabetes is chronic, irreversible, and progressive,” said Rubino. “But we have thousands of patients who once had diabetes and now do not.”

“INSUFFICIENT” EVIDENCE

Bariatric surgeons have long been prone to declaring victory against diabetes way too soon, before large-scale, long-term data proved their case. “The evidence for the success of bariatric surgery in patients with a BMI below 35 is not very strong,” said Leonid Poretsky, director of the Friedman Diabetes Institute at Beth Israel Medical Center in New York City. “Most of the studies have been very small and not well controlled.”

The American Diabetes Association rates the evidence that bariatric surgery can cure diabetes as “E,” the lowest of four grades. It calls data on patients with a BMI below 35 “insufficient,” and says the procedure cannot be recommended except as part of research.

The immediate risks of bariatric surgery are small - a 0.3 percent chance of dying within 30 days of the procedure. But a small fraction of patients develop infections, leaking from the stomach into the abdominal cavity, or gallstones, and it can cause nutritional deficiencies: There is less intestine to absorb vitamins and minerals, raising the possibility of osteoporosis and anemia.

Despite these red flags, the surgical option is attracting intense interest because the quest to cure diabetes has become almost desperate. In type-1 diabetes, the pancreas does not produce enough insulin, a hormone that moves the glucose in food into cells. In type-2 diabetes, cells become resistant to insulin. In either case, glucose remains in the blood, damaging cells and blood vessels, sometimes severely enough to cause blindness, kidney failure, or gangrene requiring foot or limb amputations.

In 2010, 8.3 percent of adults worldwide had type-2 diabetes (11.3 percent did in the United States), resulting in direct medical costs of $376 billion ($116 billion in the United States). By 2030, the global incidence is projected to rise to 9.9 percent, partly because of the rising obesity rate, with costs reaching $490 billion.

The possibility that bariatric surgery could cure diabetes emerged about a decade ago. A long-term study of thousands of patients in Sweden reported in 2004 that both gastric bypass and banding improved diabetes in many subjects. A 2008 study of 55 obese patients found that 73 percent of those who underwent gastric banding saw their diabetes disappear after two years, compared to 13 percent undergoing standard medical treatment such as medication, diet and exercise.

In 2009, surgeons at the University of Minnesota analyzed 621 mostly small studies of bariatric surgery in obese, diabetic patients. Their conclusion, reported in the American Journal of Medicine: 78 percent no longer needed medication to control their blood sugar. They’d been cured. Lap banding had the worst results, worsening diabetes in some patients.

But most patients in these studies were obese, many morbidly so. (The average BMI was 48.) The improvement in glucose control could therefore be credited to the patients’ weight loss, which averaged 85 pounds.