WASHINGTON (Reuters) - A diabetes expert group backed the use of weight-loss surgery on Monday for the treatment of type 2 diabetes in severely obese patients.

According to a statement from the International Diabetes Federation, there is increasing evidence that the health of obese people with type 2 diabetes can benefit substantially from weight-loss surgery under some circumstances.

Type 2 diabetes, which has reached epidemic proportions, is linked strongly with poor diet, lack of exercise and obesity.

Up to a third of U.S. adults could suffer from diabetes by 2050 should Americans continue to gain weight and avoid exercise, according to a projection by Centers for Disease Control and Prevention.

"Bariatric surgery for severely obese people with type 2 diabetes should be considered much earlier in management rather than held back as a last resort," said George Alberti, senior research investigator at the Imperial College, London.

"It should be incorporated into type 2 diabetes treatment protocols," he added.

Allergan Inc markets an implantable weight-loss device, Lap-Band, which got approval last month for use in patients who are less obese than the patients for which it had been approved.

The Lap-Band was earlier allowed for adults with a body mass index of at least 40, or at least 35 with one health problem. The range has now been expanded to include adults with a BMI of 30 to 40, and at least one obesity-related problem.

According to the expert group, surgery should be an accepted option in people who have type 2 diabetes and a body mass index of 35 or more.

Other companies trying to develop obesity treatments include Arena Pharmaceuticals Inc, Orexigen Therapeutics Inc and Vivus Inc.

However, the obesity sector has not seen much good news lately, with Abbott Laboratories Inc's diet drug Meridia being pulled off the U.S. market and the three experimental drugs facing regulatory hurdles.

Allergan shares were trading up 12 cents at $69.97 in afternoon trade on the New York Stock Exchange. They touched a high of $70.20 earlier in the day.

(Reporting by Esha Dey, editing by Gerald E. McCormick)