Three-fourths of obese diabetics who had weight-loss surgery were able to quit taking diabetes drugs within six months of their operation, U.S. researchers said on Monday, citing a new study.

They said the surgery may eliminate the need for chronic medications to treat the disease and reduce overall healthcare costs, providing a strong argument for insurance companies to pay for the procedures.

Once developed, diabetes and obesity are rarely reversed, Dr. Martin Makary of Johns Hopkins University in Baltimore and colleagues reported in Archives of Surgery, a medical journal.

"Until a successful non-surgical means for preventing and reversing obesity is developed, bariatric surgery appears to be the only intervention that can result in a sustained reversal of both obesity and type 2 diabetes mellitus in most patients receiving it," they wrote.

Bariatric surgery, or weight loss surgery, has increased by 200 percent during the past five years, as obese people struggled to lose weight and avoid the health complications that accompany the extra pounds — such as diabetes, heart disease, joint pain and some cancers.

There are several ways to do the surgery with the aim of giving the patient the illusion of fullness with small meals.

In one approach, an adjustable band is inserted in a small incision and wrapped around the top of the stomach during the surgery. In another, known as Roux-en-Y, the stomach is closed off near the top, creating a small pouch.

But few studies have looked at how the surgery affected health costs in type 2 diabetics.

Makary and his colleagues analyzed insurance claims data from 2,235 patients who underwent bariatric surgery during a four-year period.

They found that among the diabetic patients who had bariatric surgery, only 25 percent were taking diabetes medication six months later, and that number kept falling.

A year after surgery, fewer than 20 percent of patients were taking diabetes drugs and two years after surgery, only 15 percent were still doing so.

Healthcare costs per diabetic averaged $6,376 per year in the two years before surgery. The median cost of the surgery and hospitalization was $29,959.

Health costs increased in the year after the study by nearly 10 percent, but then fell by 34 percent in the second year after surgery and by 70.5 percent in the third year.

"Because weight loss following bariatric surgery has been observed to be sustained for decades, we believe that the protective effect against complications of diabetes is also likely to be long-term," the team wrote.

Based on the study, obese patients with diabetes should be told about the risks and benefits of bariatric surgery, and insurance companies should be encouraged to cover weight-loss surgery for appropriate patients, they said.

The National Institutes of Health recommends the surgery for someone with a body mass index of at least 40.

BMI is equal to weight in kilograms divided by height in meters squared. A person 5 feet 5 inches tall with a BMI of 40 would weigh more than 240 pounds (109 kg).

Both Johnson & Johnson and Allergan Inc make bands for weight-loss surgery.