After a nearly 80-year hunt to end the need for painful daily injections for diabetics, researchers reported Monday that an experimental oral spray successfully delivers critical insulin into the bloodstream and may spell the end of the needle.

Diabetes is the world's most common metabolic disorder, expected to afflict 300 million people by 2025. As diabetics await the breakthroughs that could cure them, they continue to give themselves shots every day to control their blood sugar levels.

Seven research papers presented Monday at the annual meeting of the American Diabetes Association in Philadelphia showed insulin by mouth had worked exactly as its makers had hoped, with the aerosolized puffs quickly passing through the mucus membranes of the cheeks and entering the bloodstream.

That method is just one contestant in a high-stakes race by drug companies to replace the syringe and tap into a worldwide market estimated at $20 billion annually.

Like most large-molecule pharmaceuticals such as vaccines and hormones, insulin cannot be taken in pill form and swallowed because the digestive tract will break it down and destroy the active elements before they can enter the bloodstream.

Currently, such drugs are administered by injection -- either by a disposable syringe, a pen/cartridge device or an implanted insulin pump. The most common methods involve patients sticking themselves, ranging from once every three days to four or five times daily.

The papers presented Monday at the world's largest diabetes scientific meeting documented the progress of a product called Oralin, made by the Toronto-based Generex Biotechnology Corp., as it wends its way through the regulatory process leading to approval by the U.S. Food and Drug Administration.

Safe and effective

The drug has now passed the first two phases of FDA tests -- indicating generally that it is safe and it works -- and is now ready for wider tests on thousands of patients.

"We have proven that it works, and there were big bugaboos about that," said the primary investigator conducting the Generex clinical trials, Dr. Sherwin Schwartz, director of the Diabetes and Glandular Disease Clinic in San Antonio.

Other experts, fearful of raising false hopes, remained cautiously optimistic.

"One has to reserve judgment until there's independent confirmation, but I must admit the data are impressive," said Dr. Richard Furlanetto, scientific director of the Juvenile Diabetes Research Foundation.

"The nice thing about the aerosol spray would be that patients could dose themselves rapidly. You're having a snack. You can take some extra insulin if you need it. You can take it right before meals or in a restaurant. No need to get out a syringe.

"There is a great need for less invasive and more convenient forms of giving insulin," Furlanetto said. "The easier we doctors can make it, the better our patients can control the disease. And that, of course, leads to fewer complications."

In diabetes, there is too much glucose (sugar) in the blood. Insulin works by stimulating the uptake of glucose into cells and by suppressing the production of glucose by the liver.

People with Type 1 (also called juvenile-onset) diabetes lose their ability to produce any insulin to trigger the conversion of food into energy. About 90 percent of diabetic patients have the much more common Type 2 (or adult-onset) diabetes. They produce enough insulin, but the cells that normally respond to it fail to do so.

Many experts believe up to 25 percent of the diabetic population is needle-phobic and hates the idea of injections. But even for those who tolerate them, the choice between injecting or inhaling would seem obvious. In the U.S. alone, a $3 billion market is at stake.

'Frightening number'

"It is estimated that 98 percent of all diabetics today are poorly managed. That is a terrible and frightening number," said Anna E. Gluskin, president and chief executive officer of Generex Biotechnology.