The results, published in Thursday's New England Journal of Medicine, are provoking fresh debate about when adjustable bands and other bariatric procedures should be offered.
It is "provocative and exciting" that surgery can prevent diabetes, but it is "impractical and unjustified" to think of doing it on millions of obese adults, Dr. Danny Jacobs, a Duke University surgeon, wrote in a commentary in the medical journal.
Dr. Mitchell Roslin, bariatric surgery chief at Lenox Hill Hospital in New York, disagreed.
"If surgery is the only treatment we have, we have to accept the cost ramifications of that" and give up "the naive notion" that we can just teach severely obese people how to lose weight, said Roslin, who consults for some makers of bariatric surgery equipment.
Millions of Americans have Type 2 diabetes brought on by obesity. Earlier this year, two studies showed that obesity surgery can reverse diabetes and keep it away for many years, possibly for good.
The new study went a step further, to see if it could prevent diabetes in the first place among people who are obese.
Researchers led by Dr. Lars Sjöström of Sahlgrenska University Hospital in Gothenburg, Sweden, tracked 1,658 patients who had bariatric surgery — mostly bands and stomach stapling — and 1,771 similar patients who just got usual care and counselling on how to lose weight.
None had diabetes when the study began. After about 10 years on average among those still in the study, 392 developed diabetes in the usual care group versus 110 in the surgery group. Researchers calculated that surgery had reduced the odds of getting diabetes by 78 per cent.
That is "absolutely remarkable," said Dr. Philip Schauer, a Cleveland Clinic surgeon who also has consulted for some surgery equipment makers and thinks surgery should be used more often for obesity.
Weight-loss surgery costs $15,000 to $25,000, and Medicare often covers it for diabetics. Proponents note that complications of diabetes and obesity are expensive, too, especially if dialysis or a kidney transplant is needed.
The government recently lowered the weight limits for gastric band surgery for those with diabetes or heart disease.
Weight-loss info: http://win.niddk.nih.gov
Body Mass Index calculator: http://www.nhlbisupport.com/bmi/bminojs.htm
New England Journal: http://www.nejm.org
Marilynn Marchione can be followed at http://twitter.com/MMarchioneAP