One year after treatment began, only 12 percent of those treated with medicines alone were at that healthy level, versus 42 percent and 37 percent of the two groups given surgery.
Use of medicines for high cholesterol and other heart risks dropped among those in the surgery groups but rose in the group on medicines alone.
"Every single one of the bypass patients who got to 6 or less got there without the need for any diabetes medicines. Almost half of them were on insulin at the start. That's pretty amazing," said a study co-leader, Dr. Steven Nissen, the Cleveland Clinic's cardiovascular chief.
An obesity surgery equipment company sponsored the study, and some of the researchers are paid consultants; the federal government also contributed grant support.
The second study was led by Dr. Geltrude Mingrone at the Catholic University in Rome, with Rubino from New York. It involved 60 patients given one of two types of surgery or medicines alone. The researchers set as their goal an A1c under 6.5 — the level at which someone is considered to have diabetes.
Two years later, 95 percent and 75 percent of the two surgery groups achieved and maintained the target blood-sugar levels without any diabetes drugs. None of those in the medicine-alone group did.
There were no deaths from surgery and only a few complications. Four patients in the Cleveland study needed second surgeries, and two in the Italian study needed hernia operations. Doctors note that uncontrolled diabetes has complications, too — many patients wind up on dialysis when their kidneys fail, and some need transplants.
An adult who has a body mass index (a calculation based on height and weight) of 30 or more is considered obese. That's 203 pounds or more for a 5-foot-9 man, for example.
The government recently lowered the criteria for use of gastric bands from a BMI of 35 down to 30 in diabetics or people with heart disease, opening the way for wider use of this and other procedures for obesity.
Dr. Alvin Powers, director of the Vanderbilt University diabetes center, said the results are very encouraging for people like those in these studies — very obese, with diabetes that can't be controlled through less drastic means.
"We still don't know the long-term outcomes of these surgeries" and whether the benefits will last for more than a few years, he said.
Others were more positive.
The studies "are likely to have a major effect on future diabetes treatment," two diabetes experts from Australia, Dr. Paul Zimmet and George Alberti, wrote in an editorial in the medical journal. Surgery "should not be seen as a last resort" and should be considered earlier in treating obese people with diabetes, they wrote.
Jon Diat is a success story. Diat, 50, who works at Citigroup and lives in New York, had been piling on pounds and pills for cholesterol and high blood pressure. After he needed an artery-opening procedure he was diagnosed with diabetes, but medicines for that failed to keep his disease under control and worsened his obesity.
"I was maxed out on the medications. It was very grim," he said. Two years ago, he had weight-loss surgery from Rubino.
"They told me, 'You're going to see rapid results,' but it was amazing. I literally lost 70 pounds in the first three months," he said. "I was off insulin within less than 72 hours of surgery. I am in complete, total remission of diabetes. My blood sugars are normal."
Now he eats right, plays tennis and hockey, walks the two miles home from work and takes 12 flights of stairs to his apartment.
"I look at this as a second chance at life," he said. "It's been liberating."
Tamikka McCray, 39, who also lives in New York and works for the city's Human Resources Administration, also had success from her surgery a year and a half ago. When she left the hospital, her diabetes had disappeared before any major weight loss had a chance to occur.
"That was the crazy part," she said. "I didn't understand that when they came in and they checked it. My sugars were normal." She added: "I left the hospital with no medication. And I haven't been on anything since."
Surgery explainer: http://win.niddk.nih.gov/publications/gastric.htm(hash)SurgAdult
Body Mass Index calculator: http://www.nhlbisupport.com/bmi/bminojs.htm
Heart meeting: www.cardiosource.org
New England Journal: www.nejm.org
Marilynn Marchione can be followed at http://twitter.com/MMarchioneAP
AP video journalist Ted Shaffrey in New York contributed to this report.
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