CHICAGO - Diabetics with stable heart disease do just as well taking drugs alone as getting quick angioplasty or bypass surgery to open blocked heart arteries, U.S. researchers said on Sunday.

They said patients advised to have angioplasty and a heart stent to restore blood flow and ease chest pain could safely wait and give drugs a chance to work.

But those with more severe disease sent for more invasive heart bypass surgery might be able to avoid a future heart attack if they have the surgery right away.

The study also found no difference in heart risks between two strategies for treating type 2 diabetes -- increasing the amount of insulin or lowering the body's resistance to its own insulin with drugs such as either metformin or GlaxoSmithKline's Avandia, also known as rosiglitazone, which had been thought to raise the risk of heart attacks.

If you have diabetes and heart disease such that a bypass surgery is a recommended procedure, you should have that early rather than delaying it, said Dr. Trevor Orchard of the University of Pittsburgh, whose study appears in the New England Journal of Medicine.

Orchard said the study, also being presented at the American Diabetes Association meeting in New Orleans, offers evidence on how best to treat people with both type 2 diabetes and heart disease. More than 65 percent of people with diabetes die from heart disease or stroke.

For GlaxoSmithKline, the study represents a positive sign that Avandia may be safer than earlier analyses had suggested.

But it may be another blow for stent makers such as Boston Scientific Corp and Johnson & Johnson, whose U.S. sales plummeted after a similar study two years ago showed stents were no better than drugs at preventing death and heart attacks in all types of heart patients.

Stents are wire mesh tubes that prop open diseased arteries after they have been unclogged during angioplasty.

QUESTIONING ANGIOPLASTY

In a commentary in the journal, Dr. William Boden of the University at Buffalo in New York said doctors should question why so many diabetics still get angioplasty.

The continued high rate of use of (angioplasty) (1.24 million procedures per year in the U.S.) and the high rate of drug-eluting stent usage strongly suggests that we critically reassess our approach to revascularization, if needed, in diabetics with coronary disease, Boden wrote.

Diabetics with stable chest pain account for about 40 percent of all U.S. patients who get angioplasty, according to Wachovia analyst Larry Biegelsen, who said the findings could cut U.S. procedures by 3 percent.

The study involved 2,368 patients who either got treated right away with angioplasty, usually with a stent, and drugs or simply got drug treatment. It found no difference in the rates of death, heart attack or stroke after five years.

Abbott Laboratories Inc spokesman Jonathon Hamilton downplayed the findings and said many patients in the study were treated with older stents. He said in an e-mail newer stents might have shown a benefit over medical treatment.

The study also looked at the risks and benefits of two strategies for controlling blood sugar in patients with type 2 diabetes, in which people lose the ability to use insulin.

One group took insulin injections or drugs known as sulfonylureas that boost the body's production of insulin. The other took insulin-sensitizing drugs like metformin or drugs known as glitazones, which include Avandia or Takeda Pharmaceutical Co's pioglitazone, brand name Actos.

Orchard said about 60 percent of patients in the insulin-sensitizing group took rosiglitazone or Avandia. He said there was no increased risk of heart attacks among patients in this group.

(Editing by Maggie Fox)

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